Defining and non-defining relative clauses

When you use it

A relative clause describes a noun from inside the same sentence: the woman who lives next door. There are two kinds, and they do different jobs. A defining clause tells the listener which person or thing you mean; without it the sentence is incomplete or unclear. A non-defining clause adds information about a noun that is already identified, such as a name or a unique thing; the sentence would still make sense without it. The difference shows in the commas, in the intonation and in the pronouns you are allowed to use.

How it is formed

Compare the same words with and without commas.

In a defining clause the relative pronoun can disappear when it is the object: the phone (that) I bought. It cannot disappear when it is the subject: the phone that broke, never the phone broke. A non-defining clause always keeps its pronoun.

The reason that is banned from non-defining clauses is historical: that is the older, tighter link and fuses with the noun; who and which can stand a little apart, which is what a comma requires.

Examples

• The woman who lives next door is a doctor.
• Anna, who lives next door, is a doctor.
• The phone that I bought last week has stopped working.
• My new phone, which cost a fortune, has stopped working.
• Tom is the friend whose car we borrowed.
• We visited the town where my mother was born.
• She cancelled the trip, which surprised everyone.
• The restaurant we liked has closed.

Common mistakes

• ✗ My mother, that works at the school, is retiring.
  ✓ My mother, who works at the school, is retiring.
  Ukrainian який and Russian который serve in every kind of relative clause, so the idea that one pronoun is restricted to one type is new. After a comma, use who or which, never that.
• ✗ The book, which I read last week, was boring. (meaning one particular book among many)
  ✓ The book which I read last week was boring.
  Russian punctuation requires a comma before который every time, and learners carry the comma into English. In English the comma is meaning, not decoration: it says the clause is extra information, which is wrong when the clause is what identifies the book.
• ✗ The man which I met yesterday is Anna's boss.
  ✓ The man who I met yesterday is Anna's boss.
  Который does not care whether the noun is a person or a thing. English does: who (or that) for people, which (or that) for things.
• ✗ The flat where I live in is very small.
  ✓ The flat where I live is very small. / ✓ The flat I live in is very small.
  Where already contains the meaning of in. Choose either where with no preposition or which / that with the preposition at the end, not both.
• ✗ Anna, who she works with me, is from Odesa.
  ✓ Anna, who works with me, is from Odesa.
  The relative pronoun is the subject of its clause, so no second subject is needed. Learners sometimes treat who as a conjunction like що / что and add the pronoun again.

Try it