Relative Clauses: Defining vs Non-Defining Meaning
Grammar Rule in 30 Seconds
Defining clauses identify exactly who/what you mean; non-defining clauses just add extra details using commas.
- Defining: No commas, 'that' is okay, essential for meaning. Example: 'The car that I bought is red.'
- Non-Defining: Use commas, 'that' is NOT okay, extra info only. Example: 'My car, which is red, is fast.'
- Omission: In defining clauses, you can drop 'who/which/that' if it's the object. Example: 'The book (that) I read.'
Overview
Use words to tell more about things. Some facts are important. Some facts are extra.
This helps people understand you. It makes your English better.
One way tells us which person you mean. You need this part. Another way gives extra info. We already know the person.
You can remove extra info. The sentence still works. Use commas for extra info. Do not use commas for important info.
How This Grammar Works
- No Commas: Defining relative clauses are never separated by commas from the noun they modify. This lack of punctuation signals that the clause is an inseparable part of the noun phrase, working directly to define or restrict its meaning. For example, in
The book that I am reading is very engaging,the clausethat I am readingtells us precisely which book is being discussed. If you removed it,The book is very engaging,the sentence would lack specific identification.
- Relative Pronouns: You can use a range of relative pronouns in defining clauses:
who(for people, as subject or object):The professor who teaches advanced physics is retiring.whom(for people, as object, more formal):The colleague whom I met yesterday is very friendly.(Less common in informal English)which(for things, as subject or object):I saw the car which won the race.that(for people or things, as subject or object, very common in informal English):This is the movie that everyone is talking about.This flexibility makesthata popular choice.whose(for possession, for people or things):She knows the artist whose paintings are exhibited in the gallery.where(for places):That's the restaurant where we had our first date.when(for times):I remember the day when we first met.
- Pronoun Omission: In defining relative clauses, you can often omit the relative pronoun (
who,whom,which,that) if it functions as the object of the relative clause. For instance,The email (that) I received was important.Here,thatis the object ofreceived. However, you cannot omit the relative pronoun if it is the subject of the relative clause. You must sayThe person who called me was polite,notThe person called me was polite.This is becausewhois the subject ofcalled.
- Always Commas: Non-defining relative clauses are always separated by commas from the noun they modify. If the clause is in the middle of a sentence, it will have a comma before it and a comma after it:
My brother, who lives in Canada, is visiting next month.If the clause comes at the end of the sentence, it will have a comma before it:I finished my report, which was due today.These commas signify that the information is supplementary and can be removed without affecting the sentence's core meaning or the identity of the noun.
- Relative Pronouns: The choice of relative pronouns is more restricted in non-defining clauses:
who(for people, subject or object):Dr. Evelyn Reed, who is a renowned historian, lectured on ancient civilisations.whom(for people, object, formal):My manager, whom I admire greatly, was promoted.which(for things, subject or object):The new library, which cost millions to build, officially opens next week.whose(for possession, for people or things):My neighbour, whose dog barks loudly, offered me earplugs.where(for places):London, where I grew up, is a bustling city.when(for times):Last Tuesday, when the storm hit, was a chaotic day.- Crucial Rule: You cannot use
thatin a non-defining relative clause. This is a strict rule in English grammar. For things, you must usewhich.
- No Pronoun Omission: You can never omit the relative pronoun in a non-defining relative clause, regardless of whether it functions as the subject or the object of the clause. The pronoun is necessary to maintain the grammatical structure of the parenthetical information.
My sister who lives in New York is visiting.(Defining) - This implies you have more than one sister, and you are specifying which sister (the one in New York) is visiting.My sister, who lives in New York, is visiting.(Non-defining) - This implies you have only one sister, and the informationwho lives in New Yorkis an extra detail about her. You would know which sister is visiting even without this information.
Formation Pattern
When To Use It
- 1The Noun Needs Identification: The clause tells your listener or reader which specific person, place, or thing you are talking about out of several possibilities. Without the clause, the noun would be too vague.
- Example:
I need the document that contains the budget figures.(There might be many documents; this clause specifies the correct one.) - Example:
The student who submitted their assignment late received a penalty.(This specifies which student, implying there were other students who submitted on time.)
- 1You are Restricting or Limiting the Noun's Meaning: The clause narrows down the scope of the noun to a specific subset.
- Example:
Only employees who have completed the training can access the system.(This limits access to a specific group of employees.)
- 1In Casual and Informal Contexts: In everyday conversation and informal writing,
thatis very frequently used for both people and things in defining clauses, and object pronouns are often omitted.
- Example:
There's the guy that fixed my computer.(Instead ofwho fixed) - Example:
Did you find the keys I left on the table?(Omittingthatorwhich)
- 1The Noun is Already Clearly Identified: The noun is a proper noun (e.g., a name of a person or place), unique, or made specific by a possessive or demonstrative adjective (e.g.,
my car,this book). The clause adds extra information but isn't needed for identification.
- Example:
Dr. Ramirez, who is my professor, gave an amazing lecture today.(Dr. Ramirez is a specific person, already identified by name. The clause adds a detail about her profession.) - Example:
My new laptop, which cost a fortune, is super fast.(You already know which laptop is being discussed, so the cost is just an additional comment.)
- 1You are Providing Additional Background or Commentary: The clause adds interesting but non-essential details, explanations, or opinions.
- Example:
The Eiffel Tower, which is in Paris, is an iconic landmark.(There is only one Eiffel Tower; its location is an extra piece of information.)
- 1In Formal Writing and Speech: Non-defining clauses with
whichfor things are particularly common in academic writing, reports, and formal presentations to add nuanced information without breaking the flow of the main argument.
- Example:
The company's latest quarterly report, which was published last Friday, shows significant growth in revenue.
Relative Pronoun Selection
| Function | For People | For Things | For Places/Time |
|---|---|---|---|
|
Subject
|
who / that
|
which / that
|
N/A
|
|
Object
|
who / whom / that / (ø)
|
which / that / (ø)
|
where / when
|
|
Possessive
|
whose
|
whose / of which
|
N/A
|
Pronoun Omission (Defining Only)
| Full Form | Short Form (Omitted) | Condition |
|---|---|---|
|
The man who I met
|
The man I met
|
Pronoun is the Object
|
|
The book that you read
|
The book you read
|
Pronoun is the Object
|
|
The man who lives here
|
NOT POSSIBLE
|
Pronoun is the Subject
|
Meanings
Relative clauses provide more information about a noun. Defining clauses limit the noun to a specific one, while non-defining clauses provide supplementary details about a noun already identified.
Defining (Restrictive)
Tells us which specific person or thing we are talking about. Without it, the sentence is incomplete or unclear.
“The students who studied hard passed the exam.”
“I'm looking for the keys that I left on the table.”
Non-Defining (Non-Restrictive)
Adds extra information about a noun we already know. The sentence still makes sense if you remove this clause.
“My brother, who lives in New York, is a chef.”
“The Eiffel Tower, which was built in 1889, is in Paris.”
Object Pronoun Omission
In defining clauses, if the relative pronoun is the object of the verb, it can be deleted.
“The movie (that) we watched was boring.”
“The person (who) I called didn't answer.”
Reference Table
| Type | Punctuation | Pronouns Allowed | Can Omit Pronoun? | Example |
|---|---|---|---|---|
|
Defining
|
No commas
|
who, which, that
|
Yes (if object)
|
The car that I like is red.
|
|
Non-Defining
|
Commas required
|
who, which, whom, whose
|
No
|
My car, which is red, is fast.
|
|
Possessive
|
Either
|
whose
|
No
|
The boy whose bike is lost.
|
|
Place
|
Either
|
where
|
No
|
The house where I live.
|
Formality Spectrum
The colleague with whom I collaborated on the project is absent. (Workplace)
The colleague who I worked with on the project is away. (Workplace)
The guy I worked with is out. (Workplace)
My project partner's ghosting today. (Workplace)
Relative Clause Decision Tree
Defining
- Essential Info Necessary to identify noun
- No Commas Flows with the sentence
Non-Defining
- Extra Info Bonus details
- Commas Separated by pauses
Defining vs. Non-Defining
Can I use 'That'?
Is there a comma before it?
Is it essential info?
Relative Pronoun Usage
People
- • who
- • whom
- • that
- • whose
Things
- • which
- • that
- • whose
- • of which
Examples by Level
The boy who is happy is my brother.
I have a dog that is big.
This is the book that I want.
The girl who lives here is nice.
The car which he bought is blue.
The man (who) I saw yesterday was tall.
I like the city where I was born.
She is the teacher who helps me.
My sister, who lives in Rome, is a lawyer.
The laptop that I use for work is broken.
London, which is the capital of the UK, is huge.
The man whose car was stolen is very angry.
The company, which was founded in 1920, is closing.
He failed his driving test, which was a surprise.
The candidate for whom I voted didn't win.
Is that the reason why you were late?
The building, the roof of which was damaged, is old.
Anyone wishing to leave early may do so.
The method by which they achieved this is unknown.
The town, where many artists live, is very vibrant.
The project, the success of which remains to be seen, is costly.
He was late, as is often the case with him.
Whosoever finds the key shall be rewarded.
The situation, albeit difficult, is not hopeless.
Easily Confused
Learners often use them interchangeably in all contexts.
Learners aren't sure when to use the object form 'whom'.
Both describe nouns but use different structures.
Common Mistakes
The man which lives here.
The man who lives here.
I like the book what you gave me.
I like the book that you gave me.
The girl she lives next door is nice.
The girl who lives next door is nice.
I saw the man who he is a doctor.
I saw the man who is a doctor.
The house that I live is small.
The house where I live is small.
This is the man who's car is red.
This is the man whose car is red.
The movie who I saw was good.
The movie that I saw was good.
My mother, that is 50, is a nurse.
My mother, who is 50, is a nurse.
Paris which is in France is beautiful.
Paris, which is in France, is beautiful.
The man, who I met him, was nice.
The man, who I met, was nice.
The car, that's engine is broken, is mine.
The car, whose engine is broken, is mine.
Sentence Patterns
The ___ who ___ is ___.
___, which is ___, is ___.
The ___ (that) I ___ was ___.
The person whose ___ is ___.
Real World Usage
My bestie, who is literally the cutest, just graduated!
I am looking for a role that allows me to use my coding skills.
The suspect, who was arrested late last night, is being questioned.
Did you find the keys I lost?
The theory, which was first proposed in 1990, remains controversial.
Take the train that goes toward the city center.
The Finger Test
No 'That' After Commas
Omission for Natural Speech
Whom is for Writing
Smart Tips
Always use a non-defining clause with commas. Proper nouns are already specific, so any extra info is just 'extra'.
Use 'whom' after prepositions like 'to', 'with', or 'for'.
Check if there is another subject immediately after it. If there is, you can usually delete it.
Use ', which' at the end of the sentence.
Pronunciation
The Comma Pause
In non-defining clauses, there is a slight drop in pitch and a brief pause where the commas are.
Relative Pronoun Reduction
In fast speech, 'that' is often pronounced with a schwa /ðət/.
Non-defining Parenthetical
My car, (which is red), is fast.
The pitch goes down for the clause and back up for the main verb.
Memorize It
Mnemonic
Defining is 'Determining' (no commas needed), Non-defining is 'Needless' (needs commas).
Visual Association
Imagine a defining clause as a wedding ring—it's essential and stays on the finger. Imagine a non-defining clause as a bracelet—it's extra, and you can take it off (the commas are the clasps).
Rhyme
If it's extra, use a comma. If it's needed, save the drama.
Story
A detective is looking for 'the man who stole the diamond' (Defining). Once he catches him, he says, 'This man, who is wearing a red hat, is the thief' (Non-defining).
Word Web
Challenge
Look at 5 objects in your room. Write one defining and one non-defining sentence for each.
Cultural Notes
British speakers are slightly more likely to use 'which' in defining clauses than American speakers, who strictly prefer 'that'.
Using 'whom' is almost exclusively reserved for formal writing or very formal speeches. Using it in casual conversation can sound pretentious.
In some dialects, 'that' is used for people more frequently than 'who' in informal speech.
Relative pronouns in English evolved from demonstrative and interrogative pronouns in Old English ('se', 'seo', 'þæt').
Conversation Starters
Tell me about a person who has influenced your life.
Describe your hometown, which I've never visited.
What's a movie that you've seen more than three times?
Think of a famous person whom you admire.
Journal Prompts
Common Mistakes
Test Yourself
My brother, ___ lives in Spain, is visiting next week.
The woman ___ car was stolen called the police.
Find and fix the mistake:
The laptop, that I bought yesterday, is very fast.
I have a friend. He speaks five languages.
Match each item on the left with its pair on the right:
The cake that I ate was delicious.
The man who lives here is nice.
This is the park ___ we first met.
Score: /8
Practice Exercises
8 exercisesMy brother, ___ lives in Spain, is visiting next week.
The woman ___ car was stolen called the police.
Find and fix the mistake:
The laptop, that I bought yesterday, is very fast.
I have a friend. He speaks five languages.
Match types
The cake that I ate was delicious.
The man who lives here is nice.
This is the park ___ we first met.
Score: /8
Practice Bank
10 exercisesThe phone ___ I bought yesterday is broken.
Which one is right?
Paris / is / which / beautiful / I / visited / , / ,
The girl which lives next door is nice.
Kucing yang sedang tidur itu milikku.
Match the items:
My mother, ___ is 60, still runs marathons.
Which sentence identifies a specific thing?
The man who is standing there is my uncle.
The company, ___ headquarters are in London, is hiring.
Score: /10
FAQ (8)
Use a comma if the information is 'extra'. If the sentence still makes sense without it, add commas. If the info is needed to know which noun you mean, no commas.
In defining clauses, yes (e.g., 'The man that I saw'). In non-defining clauses, no—you must use 'who'.
'Who' is for subjects (the person doing the action). 'Whom' is for objects (the person receiving the action). 'Whom' is mostly used in formal writing.
No. You can only drop it in defining clauses when it is the object of the sentence (e.g., 'The book I read'). You cannot drop it if it is the subject (e.g., 'The book that is on the table').
In defining clauses, 'which' can sound slightly more formal than 'that', especially in British English. In non-defining clauses, 'which' is the only option for things.
Yes! It is perfectly natural to say 'The car whose engine is broken' instead of the more clunky 'The car the engine of which is broken'.
This is a standard rule of English grammar. 'That' is considered a restrictive pronoun, meaning its job is to limit or define. Non-defining clauses don't limit, so 'that' doesn't fit.
It might change the meaning! 'My brother who is a doctor' implies you have multiple brothers and you're talking about the doctor one. 'My brother, who is a doctor,' implies you have one brother and he happens to be a doctor.
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
que / quien / el cual
English distinguishes between 'that' and 'which' based on commas; Spanish uses 'que' for both.
qui / que / lequel
French relative pronouns are determined by grammatical function (subject/object), not by the 'essentialness' of the info.
der / die / das
German requires commas for every relative clause, whereas English only uses them for non-defining ones.
Pre-nominal modifiers
Japanese uses word order (clause + noun) instead of pronouns (noun + who/which).
al-ladhi (الذي)
Arabic requires a pronoun like 'him' or 'it' inside the clause (e.g., 'the man who I saw him').
de (的)
Chinese places the description before the noun, while English places it after.
Learning Path
Prerequisites
Learn These First
Defining Relative Clauses: Identifying People & Things
Overview Defining relative clauses are essential grammatical structures in English that provide crucial, identifying inf...
Non-Defining Clauses: Adding Extra Info (with commas)
Overview Non-defining relative clauses are an essential tool in English for adding **supplementary information** about a...
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Reduced Relative Clauses - Defining and Non- Defining Relative Clauses - Advanced Grammar Lesson
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