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B1 Noun #31 most common 11 min read

runoff

Top 31

Practice it Examples Notes & Tips runoff in 30 Seconds

Explanation runoff in your Level:

At the A1 level, 'runoff' is a bit difficult, but we can understand it simply. Think of rain. When rain falls on the ground, some water goes into the dirt. But some water does not go into the dirt. It stays on top and moves. This water is called runoff. Imagine a slide at the park. When it rains, the water 'runs off' the slide and onto the grass. That is runoff. In another way, imagine a game. If two people have the same score, they need to play one more time to see who is the winner. This extra game is like a runoff. It is a second chance to find a winner. You might hear this word on the news when people are talking about rain or about people voting for a leader. Just remember: runoff is water that moves on top of the ground, or an extra vote to find a winner. It is a noun, which means it is a thing. You can say 'The runoff was big' or 'We need a runoff.' Keep it simple and think of things moving away from where they started.

At the A2 level, you can start to use 'runoff' in more specific sentences. In nature, runoff is water from rain or melting snow. It doesn't sink into the ground; instead, it flows into rivers or lakes. This is important because too much runoff can cause a flood. For example, 'The heavy rain caused a lot of runoff in the streets.' In politics, a runoff is a second election. This happens when no one wins the first time. If there are many people running for mayor, and no one gets more than half the votes, the top two people have a runoff. This is a very important word to know if you watch the news. You might see a headline like 'City to hold runoff election next month.' Remember that 'runoff' is one word when it is a noun. If you use it as an action, like 'The water will run off the roof,' you use two words. So, runoff is either moving water or a second vote. It helps us describe how things are decided or how water moves in our world.

As a B1 learner, you should be comfortable with both the environmental and political meanings of 'runoff.' In environmental science, runoff is a key part of the water cycle. It refers to the water that flows over the land surface. This is a major concern for cities because urban runoff can carry pollution like oil and trash into the ocean. You might read about 'agricultural runoff,' which is water from farms that contains chemicals. In politics, a runoff is a follow-up election held when the first round didn't produce a clear winner. For example, if a candidate needs 50% to win but only gets 45%, a runoff is held between the top two candidates. This ensures the winner has the support of most people. You will often hear this in news reports about elections in the US or other countries. It's a useful word for discussing environmental issues or current events. Notice that it's a compound noun. You can use it as a subject: 'The runoff was contaminated,' or as an object: 'The city scheduled a runoff.' It's a precise word that makes your English sound more professional and clear.

At the B2 level, you should understand the technical implications of 'runoff.' In hydrology, runoff is the 'excess' water that occurs when the soil is saturated or when the surface is impervious, like a parking lot. This is a major topic in urban planning and environmental protection. You might discuss 'stormwater runoff management' or the 'environmental impact of industrial runoff.' These phrases show a higher level of vocabulary. In politics, 'runoff' is a specific procedural term. It's often used in the context of 'non-partisan runoffs' or 'primary runoffs.' You should be able to explain why a runoff is necessary—to achieve a majority mandate. For instance, 'The runoff system prevents a candidate from winning with only a small plurality of the vote.' You can also use the word in sports or business contexts to describe a final tie-breaking round. At this level, you should be careful with the distinction between the noun 'runoff' and the phrasal verb 'run off.' You should also be aware of synonyms like 'drainage' or 'second-round voting' and know when to use each. Using 'runoff' correctly in an essay about the environment or politics will demonstrate a strong command of topical English.

For C1 learners, 'runoff' is a term that appears in complex discussions about ecology, engineering, and political science. In an ecological context, you might analyze the 'runoff coefficient' of different land types or the role of 'surface runoff' in soil erosion and nutrient leaching. You understand that runoff isn't just water; it's a vector for pollutants and a driver of geomorphological change. In political science, you can discuss the 'runoff voting' (also known as the two-round system) and its effects on voter behavior and party strategy. You might compare it to 'instant-runoff voting' (ranked-choice voting) and debate the pros and cons of each system for democratic representation. Your usage should be precise: 'The candidate's strategy shifted significantly in the lead-up to the runoff.' You should also be familiar with the word's use in more niche areas, such as 'runoff' in the insurance industry (referring to the process of a company stopping new business but continuing to pay out existing claims). At this level, you use 'runoff' naturally in both speech and writing, recognizing its various nuances and the specific professional registers in which it appears. You can handle complex sentence structures involving the word, such as 'Mitigating the deleterious effects of urban runoff requires a multi-faceted approach to civil engineering.'

At the C2 level, you possess a comprehensive and nuanced understanding of 'runoff' across all its applications. You are capable of using the term in highly technical scientific discourse, perhaps discussing 'subsurface runoff' versus 'overland flow' and their respective contributions to hydrograph peaks. You understand the mathematical modeling of runoff in watershed management. In the political sphere, you can provide a sophisticated critique of runoff systems, discussing how they might encourage or discourage strategic voting and their impact on political polarization. You are also aware of the most metaphorical or specialized uses, such as 'runoff' in finance and insurance, where it describes the winding down of a portfolio or a business entity. Your vocabulary is rich enough to use 'runoff' alongside terms like 'effluent,' 'discharge,' 'plurality,' and 'proportional representation' with perfect accuracy. You can write and speak about these topics with the authority of a native speaker or a subject matter expert. Whether you are drafting a policy paper on environmental regulations or analyzing the results of a complex multi-candidate election, 'runoff' is a tool you use with precision, style, and a deep understanding of its systemic implications. You recognize that 'runoff' is not just a word, but a concept that describes how systems—natural, political, or financial—manage excess and reach finality.

Practice it Examples Notes & Tips

runoff in 30 Seconds

Runoff is the water from rain or snow that flows over the land surface into bodies of water, often carrying pollutants or causing erosion.
In politics, a runoff is a second election held when no candidate wins a majority in the first round, deciding the final winner.
The term is essential in environmental science for water management and in democratic processes for ensuring a clear majority mandate for leaders.
It can also refer to a tie-breaking competition in sports or a specialized process in the insurance industry for winding down business.

The word runoff is a versatile noun that operates primarily in two distinct spheres: environmental science and political systems. In its most common physical sense, runoff refers to the portion of precipitation, such as rain or snowmelt, that does not infiltrate the soil but instead flows across the land surface. This phenomenon is a critical component of the Earth's water cycle, as it eventually feeds into streams, rivers, lakes, and oceans. Understanding runoff is essential for managing water resources, predicting floods, and controlling pollution, as moving water often carries contaminants like fertilizers, oil, and debris from roads and fields into natural water bodies.

Environmental Context: In urban planning, engineers must account for impervious surfaces like concrete and asphalt, which prevent natural absorption and significantly increase the volume of storm runoff, potentially overwhelming drainage systems.

Beyond the natural world, runoff describes a specific type of electoral process. A runoff election, or simply a runoff, occurs when the initial round of voting fails to produce a winner who meets a specific threshold, usually a simple majority (more than 50%). In such cases, a second round of voting is held between the top two candidates to determine the final victor. This ensures that the elected official has the support of a majority of the voters, rather than just a plurality in a crowded field. This term is also used in competitive sports or auditions where a tie-breaker is needed to decide a single winner from a group of high-performing participants.

Because neither candidate secured over fifty percent of the vote, the city will hold a runoff next Tuesday.

Political Context: Runoff elections are common in many democratic systems, particularly in primary elections in the United States or presidential elections in countries like France and Brazil.

In both contexts, the core concept involves something 'running off' or moving away from a primary state or location. In hydrology, the water moves away from the soil; in politics, the decision moves away from the initial inconclusive vote toward a final resolution. The term is widely used in news reporting, scientific journals, and political commentary. It carries a neutral to formal tone, depending on whether it is describing a natural disaster (like flash floods caused by heavy runoff) or a standard procedural step in a democratic election.

Agricultural runoff containing pesticides can have devastating effects on local aquatic ecosystems.

Scientific Usage: Hydrologists measure runoff rates to design better reservoirs and to understand how climate change affects local water cycles.

The track meet ended in a tie for first place, necessitating a runoff race to determine the gold medalist.

Urban runoff is often warmer than natural groundwater, which can thermal shock sensitive fish species.

Using the word runoff correctly requires identifying whether you are discussing water management or a secondary competition. As a noun, it functions as the subject or object of a sentence. In environmental contexts, it is often modified by adjectives like 'urban,' 'agricultural,' 'stormwater,' or 'surface.' In political contexts, it is frequently paired with words like 'election,' 'vote,' or 'primary.' Because it is a count noun in the political sense and often an uncountable noun in the environmental sense, pay close attention to articles and pluralization.

Environmental Example: Heavy spring rains led to significant runoff from the mountains, causing the river levels to rise dangerously fast.

When discussing elections, 'runoff' acts as a specific event. You can 'hold a runoff,' 'win a runoff,' or 'face a runoff.' It implies a progression from an earlier, inconclusive stage. For instance, 'The candidate failed to win outright, so she is now preparing for the runoff.' This usage is very common in news headlines during election cycles. It is important to note that a runoff is distinct from a 're-vote' caused by an error; it is a planned part of the system designed to ensure a majority mandate.

The environmental agency is monitoring the runoff from the nearby industrial site to ensure no chemicals are leaking into the creek.

Political Example: The two front-runners will meet in a runoff next month to decide who will become the next governor.

In technical writing, you might see 'runoff' used to describe the liquid that drains away from a process, such as in mining or manufacturing. In these cases, it is synonymous with 'effluent' or 'drainage.' For example, 'The runoff from the mine was highly acidic.' This highlights the word's association with movement and separation from a source. Whether you are writing a scientific report or a political analysis, 'runoff' provides a precise way to describe these secondary flows or secondary rounds of decision-making.

To reduce runoff, the city is encouraging residents to install rain gardens and permeable pavement.

Sports Context: After three rounds of golf ended in a dead heat, the players headed to the first hole for a sudden-death runoff.

The mayor's race is heading to a runoff because the incumbent only received 48% of the vote.

Melting glaciers contribute significantly to seasonal runoff in the Himalayan region.

You are most likely to encounter runoff in three specific environments: the evening news, science classrooms, and political discussions. During election seasons, especially in the United States, France, or Brazil, news anchors frequently use the term to describe upcoming second-round votes. Phrases like 'heading to a runoff' or 'runoff results' become common as the public waits for a final decision. In this context, the word carries a sense of anticipation and high stakes, as it represents the final hurdle for candidates.

News Media: 'In a surprising turn of events, the third-party candidate has forced a runoff between the two major party leaders.'

In environmental and meteorological contexts, you will hear 'runoff' during weather forecasts or documentaries about nature. Meteorologists use it to explain why certain areas are prone to flooding even after the rain has stopped—the water is still moving as runoff from higher ground. Environmental activists and scientists use the word when discussing water quality. They might talk about 'toxic runoff' or 'nutrient runoff' from farms that causes algae blooms in lakes. This usage is more technical and often carries a negative connotation related to pollution or ecological imbalance.

The local news reported that heavy runoff from the storm has washed out several rural roads.

Environmental Activism: 'We must implement stricter regulations on industrial runoff to protect our drinking water supply.'

Finally, you might hear it in academic or professional settings related to civil engineering, agriculture, or political science. Professors might lecture on the 'runoff coefficient' (the ratio of runoff to rainfall) or the 'runoff voting system.' In these settings, the word is used with precision and is often part of a larger technical vocabulary. Whether you're listening to a podcast about the climate crisis or watching a political debate, 'runoff' is a key term for understanding how systems—both natural and man-made—handle excess or inconclusive results.

The city council is debating new taxes to fund infrastructure that can handle increased runoff from new housing developments.

Academic Lecture: 'The geomorphology of this valley was shaped primarily by glacial runoff over thousands of years.'

Voter turnout for the runoff was significantly lower than in the general election.

The factory was fined for allowing chemical runoff to enter the local river system.

One of the most frequent errors involving runoff is confusing the noun form with the phrasal verb form. As a noun, 'runoff' is written as a single word without a space or hyphen (though some older British English texts may use a hyphen). As a verb, it must be two separate words: 'run off.' For example, you would say, 'The runoff (noun) was heavy,' but 'The water will run off (verb) the hill.' Using the noun form when you need a verb, or vice versa, is a common spelling mistake that can distract the reader.

Spelling Error: Incorrect: 'The water will runoff the roof.'
Correct: 'The water will run off the roof.'

Another common mistake is using 'runoff' interchangeably with 'overflow.' While they are related, they are not identical. 'Runoff' specifically refers to water that never soaked into the ground in the first place, whereas 'overflow' usually refers to water that was contained (like in a tank or a riverbank) but has now exceeded its capacity. In a political sense, some learners confuse a 'runoff' with a 'recount.' A recount is a second counting of the same votes to ensure accuracy, while a runoff is a completely new voting event with fewer candidates.

Don't confuse a runoff election with a recount; the former involves a new day of voting.

Conceptual Confusion: Incorrect: 'The river runoff flooded the town.' (Usually, you'd say the river 'overflowed' or 'flooded,' while the 'runoff' from the hills caused the river to rise.)

Learners also sometimes struggle with the countability of the word. When talking about water, 'runoff' is usually uncountable (e.g., 'There was much runoff'). However, when talking about elections, it is a countable noun (e.g., 'There were three runoffs in different districts'). Misusing the plural form 'runoffs' in an environmental context—such as saying 'The agricultural runoffs were toxic'—is technically possible but sounds awkward to native speakers, who would prefer 'The agricultural runoff was toxic' or 'The types of runoff were varied.'

The candidate is worried about the runoff, as her opponent has gained momentum.

Pluralization Tip: Use 'runoffs' only when referring to multiple distinct election events or multiple specific types of liquid discharge.

It is a mistake to think that runoff only happens in the rain; melting snow is a major source too.

The news report incorrectly used the word 'recount' when they actually meant a runoff.

Depending on the context, several words can serve as synonyms or alternatives to runoff. In environmental science, 'drainage' is a common alternative. While runoff refers to the water itself, drainage often refers to the system or process of the water moving away. 'Effluent' is another related term, but it specifically refers to liquid waste or sewage discharged into a river or the sea. 'Stormwater' is often used interchangeably with runoff in urban contexts, though stormwater specifically implies water originating from a storm event.

Environmental Comparisons: Runoff vs. Drainage: Runoff is the water; drainage is the path it takes.
Runoff vs. Effluent: Runoff is usually natural (rain/snow); effluent is usually man-made waste.

In the political arena, 'second round' is the most frequent alternative to 'runoff.' In many international contexts, especially in Europe, 'second round' is the standard term. You might also hear 'tie-breaker' in less formal contexts or in sports. In some specific voting systems, a 'runoff' might be called a 'two-round system.' If the runoff is conducted instantly on a single ballot (where voters rank candidates), it is called an 'instant-runoff,' which is a more technical and specific term in political science.

The city's drainage system was unable to cope with the sudden surge of stormwater.

Political Comparisons: Runoff vs. Second Round: These are essentially synonyms, but 'runoff' is more common in American English.
Runoff vs. Primary: A primary is an initial election; a runoff is a follow-up if the primary was inconclusive.

In sports, 'play-off' is a similar concept but usually refers to a series of games rather than a single event. A 'runoff' in sports is typically a single race or round to break a tie. Understanding these nuances helps you choose the most precise word for your specific situation. For example, describing a presidential election in France as a 'runoff' is correct, but calling it the 'second round' is more culturally aligned with how the French describe their own system. Similarly, in a laboratory, you would use 'filtrate' or 'supernatant' for liquids that have been separated, rather than 'runoff.'

The second round of the election will take place in two weeks, featuring the top two candidates.

Technical Alternatives: Surface flow: A more scientific term for runoff in hydrology.
Tie-breaker: A common term for a runoff in casual games or sports.

To prevent soil erosion, farmers use cover crops that absorb water and reduce surface flow.

The play-off system in the NBA is much more complex than a simple runoff election.

How Formal Is It?

Formal

Neutral

Informal

Child friendly

Slang

Fun Fact

The political meaning of 'runoff' is much newer than the environmental one, becoming common in the early 20th century as American states adopted new primary election rules.

Pronunciation Guide

UK /ˈrʌn.ɒf/

US /ˈrʌn.ɔːf/

The stress is on the first syllable: RUN-off.

Rhymes With

one-off spun-off son-of done-off won-off gun-off fun-off none-off

Common Errors

Stressing the second syllable (run-OFF), which makes it sound like the phrasal verb.
Pronouncing the 'o' in 'off' like the 'o' in 'go'.
Mumbling the 'n' sound in the middle.
Treating it as two separate words with equal stress.
Confusing the pronunciation with 'rough'.

Difficulty Rating

Reading 3/5

Common in news and science articles, requires some context to distinguish meanings.

Writing 4/5

Easy to misspell as two words or use the wrong countability.

Speaking 3/5

Useful for discussing current events and weather.

Listening 3/5

Clearly pronounced but can be confused with the phrasal verb.

What to Learn Next

Prerequisites

rain vote election flow winner

Learn Next

effluent plurality majority watershed erosion

Advanced

geomorphology incumbent nominee infiltration lixiviation

Grammar to Know

Compound Nouns

Runoff is a closed compound noun formed from a verb and a preposition.

Countable vs. Uncountable

'Much runoff' (water) vs. 'Many runoffs' (elections).

Phrasal Verbs vs. Nouns

Always use a space for the verb: 'The water will run off.'

Attributive Nouns

In 'runoff election', runoff acts as an adjective.

Subject-Verb Agreement

'The runoff is...' vs. 'The runoffs are...'

Examples by Level

The rain made a lot of runoff on the street.

La lluvia creó mucha escorrentía en la calle.

Noun used as the subject of the sentence.

We need a runoff to see who wins the game.

Necesitamos un desempate para ver quién gana el juego.

Countable noun with the article 'a'.

The water runoff goes into the river.

La escorrentía de agua va al río.

Compound noun phrase 'water runoff'.

Is there a runoff for the class president?

¿Hay una segunda vuelta para el presidente de la clase?

Interrogative sentence using 'runoff' as a noun.

The runoff from the snow is very cold.

El agua del deshielo es muy fría.

Noun modified by a prepositional phrase 'from the snow'.

Look at the runoff after the big storm.

Mira la escorrentía después de la gran tormenta.

Imperative sentence.

The runoff was fast and dirty.

La escorrentía era rápida y sucia.

Noun followed by two adjectives.

They will have a runoff next week.

Tendrán una segunda vuelta la próxima semana.

Future tense with 'will'.

The city built new pipes to carry the runoff.

La ciudad construyó nuevas tuberías para transportar la escorrentía.

Infinitive phrase 'to carry the runoff'.

Neither candidate won, so there is a runoff.

Ningún candidato ganó, así que hay una segunda vuelta.

Conjunction 'so' connecting two clauses.

Agricultural runoff can hurt the fish in the lake.

La escorrentía agrícola puede dañar a los peces del lago.

Adjective 'agricultural' modifying the noun.

The runoff election will be held on Tuesday.

La elección de segunda vuelta se llevará a cabo el martes.

Noun acting as an adjective for 'election'.

Scientists measure the runoff to predict floods.

Los científicos miden la escorrentía para predecir inundaciones.

Present simple tense for a general truth.

The runoff from the roof goes into a rain barrel.

La escorrentía del techo va a un barril de lluvia.

Subject-verb agreement (runoff goes).

He lost the first vote but won the runoff.

Perdió la primera votación pero ganó la segunda vuelta.

Past simple tense.

There was too much runoff for the small drain.

Había demasiada escorrentía para el pequeño desagüe.

Adverb 'too much' modifying the noun.

Urban runoff often contains oil from cars on the road.

La escorrentía urbana a menudo contiene aceite de los coches en la carretera.

Adverb 'often' used with present simple.

The mayor failed to get a majority, forcing a runoff.

El alcalde no logró obtener la mayoría, lo que obligó a una segunda vuelta.

Participle phrase 'forcing a runoff' describing the result.

We must reduce the runoff of fertilizers into the ocean.

Debemos reducir la escorrentía de fertilizantes hacia el océano.

Modal verb 'must' followed by the base verb 'reduce'.

The two top candidates are preparing for the runoff.

Los dos principales candidatos se están preparando para la segunda vuelta.

Present continuous tense.

The mountains have high runoff during the spring melt.

Las montañas tienen una gran escorrentía durante el deshielo de primavera.

Prepositional phrase 'during the spring melt'.

Voter turnout is usually lower in a runoff election.

La participación electoral suele ser menor en una elección de segunda vuelta.

Comparative adjective 'lower'.

Industrial runoff is a major source of water pollution.

La escorrentía industrial es una fuente importante de contaminación del agua.

Noun as the subject of a 'to be' sentence.

The race was so close that a runoff was inevitable.

La carrera fue tan reñida que una segunda vuelta era inevitable.

So...that construction.

Permeable pavements help to minimize storm runoff in cities.

Los pavimentos permeables ayudan a minimizar la escorrentía de tormentas en las ciudades.

Infinitive 'to minimize' following 'help'.

The primary runoff will determine the party's nominee.

La segunda vuelta de las primarias determinará al nominado del partido.

Future tense with 'will' to express certainty.

Excessive runoff can lead to severe soil erosion on hillsides.

La escorrentía excesiva puede provocar una erosión severa del suelo en las laderas.

Modal verb 'can' expressing possibility.

She managed to win the runoff despite a strong opponent.

Logró ganar la segunda vuelta a pesar de un oponente fuerte.

Preposition 'despite' followed by a noun phrase.

The runoff coefficient varies depending on the land cover.

El coeficiente de escorrentía varía según la cobertura del suelo.

Technical term 'runoff coefficient'.

The election rules require a runoff if no one gets 50%.

Las reglas electorales requieren una segunda vuelta si nadie obtiene el 50%.

Conditional sentence (Type 0/1).

Managing agricultural runoff is crucial for protecting wetlands.

Gestionar la escorrentía agrícola es crucial para proteger los humedales.

Gerund 'Managing' used as the subject.

The runoff results were announced late Saturday night.

Los resultados de la segunda vuelta se anunciaron el sábado por la noche.

Passive voice 'were announced'.

The geomorphology of the region is shaped by glacial runoff.

La geomorfología de la región está moldeada por la escorrentía glacial.

Technical vocabulary 'geomorphology'.

The incumbent's defeat in the runoff signaled a major political shift.

La derrota del titular en la segunda vuelta señaló un cambio político importante.

Possessive 'incumbent's' modifying the noun 'defeat'.

Urbanization significantly increases the peak runoff during storms.

La urbanización aumenta significativamente el pico de escorrentía durante las tormentas.

Adverb 'significantly' modifying the verb 'increases'.

The runoff voting system can sometimes lead to strategic voting.

El sistema de votación de segunda vuelta a veces puede conducir al voto estratégico.

Complex noun phrase 'runoff voting system'.

Mitigating toxic runoff requires sophisticated filtration systems.

Mitigar la escorrentía tóxica requiere sistemas de filtración sofisticados.

Present participle 'Mitigating' as a subject.

The candidate's performance in the runoff exceeded expectations.

El desempeño del candidato en la segunda vuelta superó las expectativas.

Verb 'exceeded' with abstract object 'expectations'.

Surface runoff is a primary driver of nutrient leaching in soil.

La escorrentía superficial es un motor principal de la lixiviación de nutrientes en el suelo.

Technical term 'nutrient leaching'.

The runoff was characterized by low voter participation.

La segunda vuelta se caracterizó por una baja participación electoral.

Passive voice with 'characterized by'.

The hydrograph illustrates the lag time between rainfall and runoff.

El hidrograma ilustra el tiempo de retraso entre la lluvia y la escorrentía.

Highly technical hydrological context.

A runoff election serves as a safeguard against minority rule.

Una elección de segunda vuelta sirve como salvaguardia contra el gobierno de la minoría.

Metaphorical use of 'safeguard'.

The legal framework for managing industrial runoff is quite complex.

El marco legal para gestionar la escorrentía industrial es bastante complejo.

Noun phrase 'legal framework'.

The runoff period for the insurance company lasted several years.

El período de liquidación de la compañía de seguros duró varios años.

Specialized financial/insurance meaning.

Subsurface runoff contributes significantly to baseflow in this basin.

La escorrentía subsuperficial contribuye significativamente al flujo base en esta cuenca.

Technical term 'baseflow'.

The political analyst debated the merits of instant-runoff voting.

El analista político debatió los méritos de la votación de segunda vuelta instantánea.

Compound technical term 'instant-runoff voting'.

The sudden runoff from the glacier caused a catastrophic outburst flood.

La repentina escorrentía del glaciar provocó una inundación catastrófica por desbordamiento.

Adjective 'catastrophic' modifying 'outburst flood'.

The runoff was seen as a litmus test for the new administration.

La segunda vuelta fue vista como una prueba de fuego para la nueva administración.

Idiomatic expression 'litmus test'.

Common Collocations

urban runoff

agricultural runoff

runoff election

stormwater runoff

surface runoff

force a runoff

toxic runoff

runoff primary

glacial runoff

runoff coefficient

Common Phrases

heading to a runoff

— When an election is inconclusive and a second round is certain.

With 90% of votes counted, the race is heading to a runoff.

polluted runoff

— Water flowing over land that has picked up contaminants.

Polluted runoff from the streets is killing the local fish.

runoff vote

— The actual act of voting in a second round.

The runoff vote will take place at the same polling stations.

seasonal runoff

— Water flow that happens at specific times of the year, like spring.

Seasonal runoff from the mountains fills the reservoir every May.

minimize runoff

— To take actions that reduce the amount of water flowing over land.

Planting more trees is a great way to minimize runoff.

runoff candidate

— A person who is competing in the second round of an election.

The runoff candidates are busy campaigning for the final vote.

chemical runoff

— Runoff that contains industrial or agricultural chemicals.

The lake was closed due to high levels of chemical runoff.

runoff race

— A competition held to break a tie.

The two sprinters had a runoff race to decide the winner.

control runoff

— To manage or direct the flow of excess water.

The new dam was built to control runoff from the hills.

runoff results

— The outcome of a second-round election.

The runoff results showed a clear victory for the challenger.

Often Confused With

runoff vs overflow

Overflow is water that exceeds a container; runoff is water that never entered the ground.

runoff vs recount

A recount is counting the same votes again; a runoff is a new election.

runoff vs effluent

Effluent is specifically waste liquid; runoff can be natural rainwater.

Idioms & Expressions

"run off with something"

— To steal something or to win something easily.

The thief ran off with her purse.

informal

"run off at the mouth"

— To talk too much or to talk about things one shouldn't.

He's always running off at the mouth about his coworkers.

informal/slang

"run off your feet"

— To be extremely busy and moving around a lot.

The waitresses were run off their feet during the lunch rush.

informal

"run someone off"

— To force someone to leave a place.

The farmer ran the trespassers off his land.

neutral

"run off a copy"

— To make a photocopy of a document.

Can you run off ten copies of this report for the meeting?

neutral

"run off the rails"

— To start behaving in a strange or uncontrolled way.

The project ran off the rails after the manager quit.

informal

"run off a cliff"

— To suddenly fail or decrease sharply.

Sales ran off a cliff during the economic downturn.

informal

"run off with the prize"

— To win a competition easily or unexpectedly.

The underdog ran off with the prize at the science fair.

neutral

"run off the road"

— To lose control of a vehicle and go onto the shoulder.

The car ran off the road during the heavy rainstorm.

neutral

"run off into the sunset"

— To leave and live a happy life (often romantic).

They decided to get married and run off into the sunset.

informal/literary

Easily Confused

runoff vs run-off (hyphenated)

Older or British spelling.

Modern American English prefers 'runoff' as one word.

The runoff was significant.

runoff vs run off (two words)

This is the verb form.

Runoff is a thing; run off is an action.

The water will run off the hill.

runoff vs runoff (insurance)

A very specialized meaning.

Refers to winding down a business, not water or elections.

The company is in runoff.

runoff vs outflow

Similar meaning of water moving away.

Outflow usually refers to water leaving a specific body like a lake.

The lake's outflow was blocked.

runoff vs drainage

Often used interchangeably.

Drainage is the system; runoff is the water itself.

The drainage system handles the runoff.

Sentence Patterns

The runoff is [adjective].

The runoff is fast.

There is a runoff for [event].

There is a runoff for the election.

[Adjective] runoff causes [problem].

Agricultural runoff causes pollution.

The city needs to [verb] the runoff.

The city needs to manage the runoff.

The [technical term] of the runoff is [description].

The chemical composition of the runoff is alarming.

A runoff serves as a [metaphor] for [concept].

A runoff serves as a litmus test for public opinion.

Neither [person] nor [person] won, so they will have a runoff.

Neither Smith nor Jones won, so they will have a runoff.

To prevent [issue], we must reduce [type] runoff.

To prevent flooding, we must reduce storm runoff.

Word Family

Nouns

Verbs

Adjectives

How to Use It

frequency

Common in news, science, and technical fields.

Common Mistakes

The water will runoff the mountain. → The water will run off the mountain.
You must use two words for the verb (action).
There were many agricultural runoffs. → There was much agricultural runoff.
In an environmental context, runoff is usually uncountable.
The election needs a recount to see who won. → The election needs a runoff to see who won.
A recount is for mistakes; a runoff is a new vote because no one got a majority.
The runoff election was cancelled because of the rain runoff. → The runoff election was postponed because of the storm runoff.
While grammatically okay, using 'runoff' twice for different meanings in one sentence is confusing. Use 'stormwater' or 'flooding' for one.
I am going to run-off some copies. → I am going to run off some copies.
The phrasal verb 'run off' (to copy) should always be two words.

Tips

Noun vs. Verb

Remember: 'Runoff' is a thing (the water or the election). 'Run off' is the action. Never write 'The water will runoff' or 'The run off was heavy.'

Environmental Use

When talking about the environment, runoff is usually something we want to 'control' or 'reduce' because it carries pollution.

Political Use

In politics, a runoff is a 'second chance' to get a clear winner. It's very common in the US and France.

No Hyphen

In modern American English, avoid the hyphen. Write 'runoff', not 'run-off', unless your specific style guide requires it.

Technical Terms

Use 'surface runoff' in scientific writing to be more precise about water moving over the land.

Stress the Start

Always put the emphasis on the first part of the word: **RUN**-off. This helps distinguish it from the verb phrase.

Adjective Use

You can use runoff as an adjective, as in 'runoff election' or 'runoff water'. This is very common.

News Keywords

When you hear 'runoff' on the news, listen for 'majority' or '50%'. This will confirm they are talking about an election.

Hydrology

If you study engineering, learn the term 'runoff coefficient'. it's a key concept in managing water.

Insurance/Finance

Be aware that in business, 'runoff' means closing down a part of a company slowly. It's a very specific professional term.

Memorize It

Mnemonic

Think of water that 'runs' because it can't 'sit' in the ground. Or a candidate who has to 'run' a second time because they didn't finish the race.

Visual Association

Imagine a rain gutter on a house. The water 'running off' the roof is runoff. Now imagine two people in a race who cross the line at the same time and have to 'run' again.

Word Web

Water Election Pollution Majority Rain Candidate Erosion Second Round

Challenge

Try to use 'runoff' in two different sentences today: one about the weather and one about a competition or choice.

Word Origin

The word 'runoff' is a compound noun formed from the phrasal verb 'run off'. It first appeared in the mid-19th century in the United States.

Original meaning: Its earliest recorded use was in the context of water flowing off the land, particularly in agricultural and geological descriptions.

English (Germanic origin).

Cultural Context

No specific sensitivities, but be aware that 'runoff' in an environmental context often implies pollution, which can be a sensitive topic for industries.

In American English, 'runoff' is the standard term. In British English, 'second round' is more common for elections.

The 2021 Georgia Senate runoff elections, which were watched globally. The Clean Water Act in the US, which regulates industrial runoff. The movie 'The Campaign' features a fictionalized runoff election.

Practice in Real Life

Real-World Contexts

Environmental Science

mitigate runoff
polluted runoff
runoff control
surface runoff

Politics

runoff election
force a runoff
runoff primary
win the runoff

Urban Planning

stormwater runoff
impervious surfaces
drainage systems
urban runoff

Sports

runoff race
tie-breaker
deciding round
final runoff

Agriculture

nutrient runoff
fertilizer runoff
soil erosion
irrigation runoff

Conversation Starters

"Did you hear that the mayoral race is going to a runoff?"

"How does your city handle all the runoff from heavy rainstorms?"

"Do you think runoff elections are a fair way to choose a leader?"

"Have you ever seen a runoff race in a track and field event?"

"What are some ways farmers can reduce chemical runoff into rivers?"

Journal Prompts

Describe a time you saw heavy runoff after a storm. What did it look like?

If you were a politician, would you prefer a runoff system or a simple majority system? Why?

Research a local water body. Is it affected by urban or agricultural runoff?

Write about a competition you were in that needed a tie-breaker or a runoff.

How can individuals help reduce polluted runoff in their own neighborhoods?

Frequently Asked Questions

10 questions

As a noun, it is one word: 'runoff'. As a verb, it is two words: 'run off'. For example, 'The runoff (noun) is high' but 'The water will run off (verb) the roof.'

A runoff election is a second round of voting held when no candidate receives a majority (usually more than 50%) in the first round. Only the top candidates compete in the runoff.

It is often considered harmful because it carries fertilizers and pesticides from farms into rivers and lakes, which can kill fish and cause algae blooms.

Urban runoff is rainwater that flows over city surfaces like roads and parking lots. It often picks up oil, trash, and chemicals before entering the sewer system.

Yes, 'runoffs' is used when referring to multiple election events. In environmental contexts, it is usually uncountable, but you might say 'different types of runoffs' in a technical report.

In sports, yes, they are very similar. In politics, a runoff is a formal second election, while a tie-breaker might be a more informal way to decide a winner.

You can reduce runoff by using permeable surfaces, planting trees, and creating rain gardens that allow water to soak into the ground instead of flowing away.

Instant-runoff is a voting system where voters rank candidates by preference. If no one wins a majority, the bottom candidates are eliminated and their votes are redistributed instantly.

It is a neutral to formal word. It is perfectly appropriate for news reports, scientific papers, and professional discussions.

No, it can also come from melting snow or ice, which is often called 'snowmelt runoff' or 'glacial runoff'.