Defining Relative Clauses

What is a Defining Relative Clause?

A defining relative clause (often called a restrictive relative clause) gives absolutely essential, identifying information about a noun. It tells us exactly which specific person, thing, time, or place we are talking about.

If you remove a defining relative clause from a sentence, the core meaning of the sentence collapses and becomes vague or incomplete.

Consider this vague sentence:

The woman is a renowned doctor. (Which woman? We have no idea.)

Now, attach a defining relative clause:

The woman who lives next door to me is a renowned doctor. (Now we know exactly who she is!)

The clause "who lives next door to me" defines the subject. You cannot remove it without losing critical context.

Defining Relative Clause Structure and Formula

A defining relative clause usually sits immediately next to the noun it modifies.

S + (Relative Pronoun + V + O) + V + O (If modifying the subject)
S + V + O + (Relative Pronoun + S + V) (If modifying the object)

Crucial Punctuation Rule: Do not ever use commas to separate a defining relative clause from the rest of the sentence. The lack of commas proves the information is essential.

List of Relative Pronouns Used with Defining Clauses

We use specific pronouns to initiate these defining clauses based on the noun being described.

How to Omit the Relative Pronoun in a Sentence

A major hallmark of advanced English fluency is knowing when to completely remove (omit) the relative pronoun (who, which, or that) to make the sentence sound much more natural.

The Golden Omission Rule: You can omit the relative pronoun only when it acts as the object of the relative clause. You cannot omit it if it acts as the subject of the relative clause.

Exception 1: When you CAN remove the pronoun

If the relative pronoun is immediately followed by a new Subject + Verb (S + V), then the pronoun is the object and can be deleted.

• Original: This is the cake which I made. (pronoun "which" is followed by subject "I")
• With omission: This is the cake I made. (Highly natural)

Exception 2: When you CANNOT remove the pronoun

If the relative pronoun is immediately followed by a Verb (V), it is acting as the subject. Do not remove it.

• Original: The man who lives next door is friendly. (pronoun "who" is followed by verb "lives")
• Incorrect omission: The man lives next door is friendly. (Grammatically broken)

How to Tell the Difference Between Defining and Non-Defining Relative Clauses

Understanding the difference between defining and non-defining clauses is essential for punctuation and clarity.

Frequently Asked Questions

Can I use "what" as a relative pronoun in a defining clause?

No. This is a very common grammatical mistake. You must use "which" or "that" to refer back to a specific noun. Incorrect: The car what I bought is red. Correct: The car that I bought is red.

Is "whom" required in defining relative clauses?

In strictly formal written grammar, "whom" is used instead of "who" if the pronoun is the object of the clause (e.g., "The man whom I saw"). However, in modern English, "who" or "that" is much more common, or you can just omit the pronoun entirely ("The man I saw").

Why is "that" used so often?

"That" is the ultimate utility pronoun for defining relative clauses. It can universally replace "who" (for people) or "which" (for things), making it incredibly convenient for speakers to use seamlessly.

Summary & Cheatsheet for Defining Relative Clauses

💡 The key takeaway: If the relative clause gives crucial information required to identify the noun, it is a defining clause. Strip away the commas, and feel free to drop the pronoun if a subject immediately follows it!