일정하다

The Korean adjective 일정하다 (il-jeong-ha-da) is a foundational word that every learner must master because it describes the very fabric of stability and predictability in our lives. At its core, it translates to being 'constant,' 'fixed,' 'regular,' or 'uniform.' Derived from the Hanja characters 一 (일 - one) and 定 (정 - fix/decide), the word literally suggests a state that has been 'fixed as one'—meaning it does not fluctuate, change, or deviate from a set standard. In a world that is often chaotic, Koreans use this word to find comfort in things that remain the same. Whether you are talking about the steady rhythm of a heart, the fixed price of a subway fare, or the consistent quality of a grandmother’s cooking, 일정하다 is the go-to descriptor.

Physical Properties

When describing scientific or physical phenomena, this word denotes a lack of variance. For example, a 'constant temperature' (일정한 온도) or 'constant speed' (일정한 속도) uses this adjective to show that the measurements do not go up or down.

Beyond physical science, the word is ubiquitous in discussing routines and habits. In Korean culture, having a 'regular life' (일정한 생활) is highly valued as a sign of discipline and health. If you wake up at 6 AM every day, eat at noon, and sleep at 10 PM, your daily routine is 일정하다. It implies a sense of reliability. Employers look for workers whose performance is 일정하다, meaning they don't have 'on' and 'off' days but rather provide a steady output of quality work. This nuance of 'reliability' is what separates it from mere 'sameness.'

Social and Economic Use

In economic contexts, it refers to fixed rates or steady income. If you have a 'fixed salary' that doesn't change based on commissions, you have an '일정한 수입'. In social settings, it can describe a person's temperament—someone who is 'steady' and not prone to mood swings.

Finally, the word appears in formal logic and mathematics. When a value is assigned and does not change throughout an equation, it is 일정하다. This breadth of use—from the kitchen to the laboratory to the bank—makes it an indispensable part of the Korean vocabulary. It bridges the gap between 'static' and 'reliable,' providing a way to talk about the things we can count on in a changing world.

Comparative Nuance

Unlike '똑같다' (to be exactly the same), '일정하다' focuses on the lack of change over a period or across a range. It’s not just about identity, but about the quality of being unwavering or uniform in distribution.

Using 일정하다 correctly requires understanding its three primary grammatical roles: as a predicate (it is constant), as a modifier (a constant thing), and as an adverb (to act constantly). Because it is a descriptive verb (adjective), it follows standard conjugation rules. However, its usage is often paired with specific nouns to create set expressions that are vital for natural-sounding Korean.

The Predicative Form (-다)

When you want to state that something 'is' constant, you use the predicative form. In polite speech, this becomes '일정해요' (present), '일정했어요' (past), or '일정할 거예요' (future). This is used for observations: 'The quality is constant' (품질이 일정해요).

The most common way you will encounter this word is in its attributive form: 일정한. By adding the suffix '-ㄴ' to the stem '일정하-', it becomes an adjective that modifies the following noun. This is used to mean 'a certain amount of,' 'a fixed,' or 'a regular.' For instance, '일정한 장소' means 'a fixed place' or 'a designated spot.' If a teacher says students must arrive at '일정한 시간,' they mean 'a fixed/set time.'

The Adverbial Form (-게)

To describe 'how' an action is performed, use '일정하게'. This is essential for instructions. 'Please cut the vegetables at a constant/regular size' (야채를 일정하게 썰어 주세요). It implies maintaining a rhythm or a standard throughout the action.

Another advanced usage involves the negative form 일정하지 않다. In Korean culture, variability is often seen as a lack of stability. Saying someone’s mood is '일정하지 않다' (not constant) is a polite way of saying they are unpredictable or flighty. Similarly, describing the weather as '일정하지 않다' means it is erratic. This negative construction is very common in news reports regarding economic trends or climate change.

Formal Contexts

In legal or academic writing, '일정한' is used to define parameters. '일정한 요건을 갖추다' means 'to meet certain requirements.' Here, it doesn't just mean 'fixed' but 'specifically designated' by a rule or law.

To master this word, practice using it with nouns like '속도' (speed), '온도' (temperature), '간격' (interval), and '수준' (level). These pairings are the 'bread and butter' of the word's usage. Once you can describe the 'fixed speed' of a car or the 'regular intervals' of a bus, you have grasped the essence of how 일정하다 functions in daily Korean life.

If you step into the world of Korean media or daily life, 일정하다 will start appearing everywhere, often in places you wouldn't expect. It is a word that moves seamlessly between high-level academic discourse and the casual chatter of a marketplace. Understanding where you hear it helps you grasp the cultural value placed on consistency and order in Korean society.

The Workplace and Professional Life

In a Korean office, '일정하다' is used to evaluate performance and processes. A manager might praise a worker whose quality of work is '일정하다', meaning they are reliable. You'll also hear it in meetings regarding '일정한 규칙' (fixed rules) or '일정한 절차' (certain procedures) that must be followed. It provides a sense of professional standard.

In the news and documentaries, 일정하다 is the standard word for reporting scientific data or economic trends. Weather reporters use it to describe temperatures that remain 'constant' throughout the day. Financial analysts use it to describe 'steady growth' or a 'fixed exchange rate.' If you are watching a documentary about nature, the narrator might describe the 'regular migration' (일정한 이동) of birds. The word carries an air of objective observation and authority.

Health and Lifestyle

Doctors and health influencers in Korea frequently use this word. They emphasize '일정한 수면 시간' (regular sleep hours) and '일정한 식사 시간' (regular meal times) as the keys to longevity. In this context, the word is synonymous with 'healthy discipline.' If someone asks why you look so healthy, you might answer that your lifestyle is '일정하다'.

In K-Dramas and movies, you might hear this word in a more psychological sense. A character might describe another's personality as '일정하다' to mean they are predictable or 'the same as always.' While it can be a compliment (reliable), in some romantic contexts, it might imply that the person is boring or lacks spontaneity. However, more often than not, it is used to describe the 'steady' heart of a loyal person whose feelings are '일정하다' (unwavering).

Public Announcements

When you are at a train station or airport, you might hear about trains running at '일정한 간격' (regular intervals). This usage is very formal and helps passengers understand the frequency of service. It’s a word that builds trust in public infrastructure.

While 일정하다 might seem straightforward, many learners stumble over its specific nuances and grammatical restrictions. The most common pitfall involves confusing the adjective 일정하다 with the noun 일정. Although they share the same Hanja root, their meanings in modern Korean have diverged significantly, leading to embarrassing or confusing errors in conversation.

Mistake 1: Confusing '일정' (Noun) with '일정하다' (Adjective)

In Korean, '일정' (日程) as a noun means 'schedule' or 'itinerary.' Learners often try to say 'The schedule is busy' by saying '일정하다 바빠요,' which is incorrect. You must use the noun '일정' for schedules. '일정하다' exclusively means 'to be constant/fixed.' To say a schedule is fixed, you would say '일정이 정해졌다' or '일정이 일정하다' (though the latter is redundant).

Another frequent error is using 일정하다 when 규칙적이다 (to be regular/follow a rule) is more appropriate. While they are close, 규칙적이다 focuses on the pattern (e.g., every Monday), while 일정하다 focuses on the state of not changing. If you want to say your heartbeat is 'regular' in a rhythmic sense, 일정하다 is great. But if you want to say you go to the gym 'regularly' (on a schedule), 규칙적으로 is often better.

Mistake 2: Misusing the Attributive '일정한' as 'Some'

In English, we often use 'a certain' to mean 'some random thing' (e.g., 'A certain person called'). In Korean, if you use '일정한 사람,' it implies a 'fixed/standard person,' which sounds strange. For 'a certain/some random' person, you should use '어떤'. Use '일정한' only when you mean a 'fixed' or 'specific designated' amount or type.

Learners also struggle with the adverbial form '일정하게' vs the adjective form '일정한.' Remember: use '일정한' to describe a noun (a fixed price - 일정한 가격) and '일정하게' to describe an action (to pay a price regularly - 일정하게 내다). Mixing these up can make your sentence grammatically 'broken' and hard for native speakers to parse quickly.

Mistake 3: Over-relying on '똑같다'

Beginners often use '똑같다' (exactly the same) for everything. However, '똑같다' is very strong. If you say the temperature is '똑같다', it means it hasn't moved 0.1 degrees. '일정하다' is more natural for saying the temperature is 'steady' or 'stable' within a normal range.

To truly master 일정하다, you must see how it sits in the ecosystem of similar Korean words. Korean has a rich vocabulary for describing states of being, and choosing the right synonym can change the tone of your sentence from 'scientific' to 'emotional' to 'practical.' Here is a comparison of the most common alternatives.

일정하다 vs 규칙적이다 (Regular)

These are the most frequently confused. 일정하다 means 'constant' or 'fixed'—the state doesn't change. 규칙적이다 (規則的) means 'regular' in the sense of following a rule or a pattern.
• 일정한 속도: A constant speed (e.g., 60km/h without stopping).
• 규칙적인 운동: Regular exercise (e.g., every Monday and Wednesday).

Another important alternative is 변함없다 (unvarying/unchanging). This is a pure Korean word (not Hanja-based) and carries a more emotional or poetic weight. While you wouldn't use 변함없다 to describe a mathematical constant, you would use it to describe a long-lasting friendship or a person’s loyal character. 일정하다 is objective; 변함없다 is subjective and warm.

일정하다 vs 고정되다 (Fixed/Fastened)

고정되다 (固定) specifically means to be physically fixed in place or to be 'locked in.' You use '고정되다' for a camera on a tripod or a fixed interest rate in a bank contract. '일정하다' is more about the quality of being fixed, whereas '고정되다' is about the action of having been fixed.

Advanced Alternative: 균일하다 (Uniform)

균일하다 (均一) is used when something is uniform across its entirety. For example, if the color of a wall is the same everywhere, it is '균일하다'. '일정하다' is more about time (staying the same), while '균일하다' is more about space or distribution (being the same across the whole).

Finally, consider 꾸준하다 (steady/consistent). This is almost exclusively used for human effort and persistence. If you study Korean for 1 hour every day without fail, you are '꾸준하다'. You wouldn't say your study time is '일정하다' (though it is), you would say you are '꾸준히 공부한다' to emphasize your hard work and dedication. Choosing 꾸준하다 adds a layer of praise for the person’s character.