Defining and non-defining relative clauses

Identification of defining and non-defining relative clauses

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Introduction to relative clauses

A defining relative clause gives essential information about who or who we are describing in a sentence, whereas a non-defining relative clause just gives us more information about who or what we are describing, therefore you could leave it out of the sentence and the sentence would still make sense and it would still be clear who or what we are describing.

We cannot leave out a defining relative clause because we need it in order to make it clear who or what we are talking about.

Besides, a non-defining relative clause is separated from the main part of the sentence by commas. A defining relative clause is not separated from the main part of the sentence by commas. We separate a non-defining relative clause from the main part of the sentence by commas because it is additional information, whereas we don´t separate a defining relative clause from the main part of the sentence by commas because it is essential information which is needed to clarify who or what we are speaking about.

Look at these sentences:

1. Children who hate chocolate are uncommon. (In this example, we use a defining relative clause who hate chocolate because it tells the listener(s) which children you are speaking about)

2. My car, which is blue, is very expensive. (This is non-defining because the relative clause «which is blue» does not tell the listener anything necessary about your car, the main message is that it is very expensive, the colour is just more information).

3. The computer which is broken is an Apple iMac. (This is defining because you are pointing out which computer is an Apple iMac. Perhaps you are in a room full of computers and you want to tell the listener which computer is an Apple iMac, you can do so by telling him it is the one that is broken).

4. Her mom, whose shop was burnt last week, has relocated. (This is non-defining because you are not identifying which mom you are talking with the relative clause. The fact that you said «her mom» tells the listener which mom you are talking about.

Another important point to understand is that we can use the relative pronoun ‘that’ instead of ‘who’ or ‘which’ in defining relative clauses but not in non-defining relative clauses. e.g An elephant is an animal that lives in hot countries.

A big rule of thumb:

A defining relative clause leaves room for a question (which one?) because a piece of information must be provided to make the sentence clear. A non-defining relative clause is marked off by commas.

Other uses of "that"

'That' is often used to introduce defining relative clauses when they follow the words something, anything, everything, nothing, all or a superlative. It may be omitted when it is not the subject of the clause.

Some examples are:

1. There's something (that) you should know.

2. It was the best film (that) I've ever seen.

3. Do you have anything that will help my throat?

4. Everything (that) you say seems silly to me.

Do not forget the rule of thumb. In the questions below, identify the defining and non-defining relative clauses:

1. The reason why I came here today is not important.

2. They live in a house whose roof is full of holes.

3. They went to a concert at the new arena, which was built last year.

4. Bob's mum, who is a musician, has lost her car keys.

5. The shoes which I bought yesterday are very comfortable.

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With love and everything English,

Francis