A defining clause (also called a restrictive clause) is a type of relative clause that specifies or limits the meaning of a noun. It provides essential information needed to identify exactly which person, thing, or group is being referred to.

What Are Defining Clauses?

Defining clauses give critical details that restrict the meaning of the noun they modify.
Without the defining clause, the meaning of the sentence would be incomplete or unclear.
They usually begin with relative pronouns like who, whom, which, or that.
Unlike non-defining clauses, defining clauses are not set off by commas.

Examples of Defining Clauses

The man who is wearing a hat is my uncle.* (The defining clause tells us which man.)
I want the book that has a blue cover.* (The defining clause specifies which book.)
People who speak two languages have an advantage.* (The clause defines which people.)

How Defining Clauses Work

The defining clause immediately follows the noun it modifies.
It narrows down or specifies the noun's meaning.
The noun plus the defining clause together form a more precise noun phrase.

More Examples

Students who study hard usually get good grades.*
The house that Jack built is old.*
The car which is parked outside belongs to my aunt.*

Where does the defining clause appear in relation to the noun it modifies?

Separated by a comma from the noun.

Immediately after the noun.

At the beginning of the sentence.

At the end of the sentence only.

Immediately after the noun.

Defining clauses come right after the noun they describe to clearly specify which person or thing is meant.

Relative Pronouns in Defining Clauses

Pronoun	Used For	Example
who	People (subject)	The woman who called you is here.*
whom	People (object)	The man whom you met is a doctor.*
which	Things and animals	The cake which she made was delicious.*
that	People or things	The book that I borrowed is missing.*

Notes

That is often preferred in defining clauses for both people and things.
Whom is more formal and less commonly used in everyday speech.

Punctuation Rules

Type of Clause	Commas?	Example
Defining (restrictive)	No commas	The students who arrived late missed the bus.*
Non-defining (non-restrictive)	Yes, with commas	My brother, who lives in New York, is visiting.*

When to Omit the Relative Pronoun

If the relative pronoun is the object of the clause, it can often be omitted.
If it is the subject, it cannot be omitted.

Examples

With Pronoun	Pronoun Omitted
The book that I read was interesting.*	The book I read was interesting.*
The woman who lives next door is friendly.*	Cannot omit who (subject).*

Summary

Defining clauses are essential for identifying exactly which person or thing is meant.
They are introduced by relative pronouns who, whom, which, or that.
They are never separated by commas.
Omitting the relative pronoun is possible only when it functions as an object within the clause.

Last updated: Wed Jun 18, 2025

English

Defining Clauses