B1 · Intermediate TOEIC 405–600 IELTS 4.0–5.0 Clauses & Conditionals

Defining Relative Clauses

Clauses with who, which, that defining exactly which person or thing is meant — no commas.

What is a Defining Relative Clause?

A defining relative clause gives essential information about a noun. It tells us exactly which person or thing we are talking about. Without this clause, the sentence would be unclear or incomplete.

Imagine you are in a room full of people.

The woman is a doctor. (Which woman?)

Now, let's add a defining relative clause to identify her:

The woman who lives next door is a doctor. (Now we know which one!)

The clause "who lives next door" is essential. If we remove it, we lose the specific meaning.

Relative Pronouns for Defining Clauses

We use different pronouns to introduce a defining relative clause.

Pronoun Use Example
who People (subject or object) The man who called you is my boss.
which Things (subject or object) This is the cake which I made.
that People or things (informal) He's the artist that painted this. / I read the book that you recommended.
whose Possession (for people/things) She's the student whose project won the award.
where Places This is the park where we met.
when Times I remember the day when we first met.

Key Rule: Do not use commas to separate a defining relative clause from the rest of the sentence.

Omitting the Relative Pronoun

This is a key feature of defining clauses. You can (and often should) remove the relative pronoun (who, which, or that) when it is the object of the clause.

The pronoun is the object if it is followed by a noun or another pronoun (the subject of the clause).

When you CAN omit the pronoun:

  • Original: This is the cake which I made.
    • ("which" is the object, "I" is the subject)
  • With omission: This is the cake I made. (Sounds more natural)

  • Original: He is the man who we met yesterday.

    • ("who" is the object, "we" is the subject)
  • With omission: He is the man we met yesterday.

When you CANNOT omit the pronoun:

You cannot remove the pronoun when it is the subject of the clause.

The pronoun is the subject if it is followed directly by a verb.

  • Original: The man who lives next door is friendly.
    • ("who" is the subject of "lives")
  • Incorrect: The man lives next door is friendly. (This makes no sense.)

Common Errors and How to Fix Them

✗ Incorrect ✓ Correct Why
The book, that I'm reading, is great. The book that I'm reading is great. Defining clauses do not use commas.
She is the person which helped me. She is the person who helped me. Use "who" or "that" for people, not "which."
The man lives there is my uncle. The man who lives there is my uncle. You cannot omit the pronoun when it is the subject of the relative clause.
I liked the movie who you suggested. I liked the movie which/that you suggested. Use "which" or "that" for things, not "who."

Summary

Feature Rule Example
Purpose Provides essential information to identify a noun. The keys that I lost are on the table.
Commas Never use commas. The student who sits here is named Alex.
Pronoun Omission Omit the pronoun only when it's the object of the clause. This is the song (that) we love.

💡 The key takeaway: If the information is necessary to know which one, it's a defining clause. No commas, and you can often drop the pronoun if it's the object.