Non-Defining Relative Clauses

Non-Defining Relative Clause Definition and Examples

Non-Defining Relative Clauses

Non-Defining/Non-Restrictive Relative Clause Definition

A relative clause that is not used to identify a particular person or thing but whose purpose is to provide further information about it is called a non-defining relative clause. The relative pronouns who, which, and whose and the relative adverb where are used to begin a non-defining relative clause.
This type of relative clause is not essential for understanding a sentence. A non-defining relative clause is also called a non-restrictive relative clause. In the case of a non-defining relative clause, a comma is usually required before and after the relative clause. Let’s explain the purpose of non-defining relative clauses with some examples.
Mr. Amjad is my cousin.
The meaning of this sentence is clear. If we want to add some extra information to this sentence, we need to add a relative clause. To this sentence, let’s add the relative clause ‘who works part-time in a shop.’
Mr. Amjad, who works part-time in a shop, is my cousin.
In this example, we set off the clause with commas. That means the information we added is nonessential and could be left out without losing the sentence’s meaning.
My friend, who came from London, makes delicious dishes.
(The relative clause in this sentence does not identify the person, i.e., my friend but just comments about him.)
  • Employees, who are mostly aged, want to express their opinion. 
  • Modern computers, which were introduced at the beginning of the 21st century, have become more and more expensive.
The parts written in bold in both sentences are relative clauses. In the first example, the information related to age expressed by the relative clause is not an essential bit of information. 
In the second example, it is clear that it is modern computers in general, not modern computers from the beginning of the 21st century, that are becoming more and more expensive. These relative clauses can be omitted without making the sentence meaningless. 
Compare the following two examples.
  • People who eat less have good health.
  • Auckland, where we spent two years, is one of the most beautiful cities in the world.
In the first of these examples, the information expressed by the clause ‘who eat less’ is essential. If we remove it from the sentence, the sentence will become ‘people have good health.’ That does not make complete sense.
In the second example, the clause ‘where we spent two years’ isn’t essential and is therefore set apart from the rest of the sentence by commas.

Use of Relative Pronouns in Non-Defining/Non-Restrictive Relative Clauses

Whether defining or non-defining, every relative clause begins with relative pronouns such as who, whom, which, and that. We use the relative pronoun ‘who’ to refer to people, not things. The pronoun ‘whom’ is used when the person we refer to is the object of the relative clause.
The relative pronoun who is used as the subject and who or whom is used as the object of the clause. But ‘which’ can be the subject or object of the clause.
  • I spoke to Sara, who had recently been mugged.
(The pronoun ‘who’ in the relative clause refers to a person, i.e., Sara)
  • The criminal whom the police had been following was arrested.
(The pronoun ‘whom’ in the non-defining relative clause refers to a person, i.e., criminal.)
On the other hand, the pronoun ‘which’ is used to refer to things, not a person.
  • My watch, which I bought yesterday, was stolen.
Some grammarians suggest the use of pronoun which or who in defining relative clauses only, and the use of that only in non-defining relative clauses, which is not correct.
The relative pronouns we have discussed so far refer to a single person or thing. In non-defining relative clauses, these relative pronouns may refer to many people or things. To say how many people or things the relative pronouns refer to in non-defining relative clauses, we need to use quantifiers. In such a case, the pronoun who and which become of whom and of which, respectively.
  • I lived with many men, all of whom, were very old.
  • I saw many students, none of whom, respected their teacher.
  • My dad and cousin, both of whom live abroad are coming to visit.
  • I have sold many expensive suits, the most expensive of which are sold today.
  • I watched many movies, some of which, were very heartbroken.
  • David has three phones, two of which, are broken.
  • The proper growth of a child’s bones is influenced by many factors, most of which we have no control over.
In these sentences, the words all, none, both, some, most, and two are quantifiers followed by of + relative pronoun that tell the relative pronoun refers to more than one person or thing.
It is more common to begin a relative clause with relative pronouns. But besides relative pronouns, the following phrases can also be used to begin non-defining relative clauses. 
at which point/time
during which time
in which case
by which point/time
  • The upcoming departmental visit to Australia is in four years, by which time my baby boy will be 7.
  • It might be heavy rain next week, in which case we won’t attend the meeting.
  • A small baby ran towards my bike, at which point I drove away the bike quickly.
  • I hadn’t seen his brother for eight years, in which time I had got two degrees.
Note that the relative pronouns introducing the non-defining relative clause cannot be omitted.

Punctuating Non-Defining Relative Clauses

The correct punctuation of a non-defining relative clause depends on its position in a sentence. The non-defining relative clause has possibly two positions in a sentence. It can come in the middle or at the end of a sentence. If it comes in the middle, a comma should go at both ends, but a comma should be placed at the end of the main clause if it comes after the whole main clause.
  • The bike, which was on the footpath, belongs to my brother.
(Since the relative clause appear in the middle, a comma goes at both ends of the non-defining relative clause)
  • Almost all the thieves in the entire city are arrested, which is an outstanding achievement.
(The relative clause comes at the end, so we put a comma at the end of the main clause.)
  • His flat, which was by the national highway, was beautiful.

Examples of Non-Defining Relative Clauses

The following sentences contain relative clauses that give extra information about the nouns. You’ll notice that each sentence will still make sense even if we remove the relative clauses because we deal with non-defining relative clauses. 
  • The woman lives on the third floor, whose height is the same as mine, invited me for dinner yesterday.
  • The film, which I watch every time, is shown in a hotel next Friday.
  • Ahmad, who had been watching movies, suddenly left the room.
  •  I received an offer of ten thousand dollars for the car, which I accepted.
  • That law course, which we took seven years ago, is no longer available at the university.
  • Mr. Adam, whose brothers are both doctors, got the first position in his medical class.
  • A young man, who lives next street, broke his hand last Friday.
  • The paper, which we attempted, was too lengthy.
  • People, who park illegally, are fined.
  • My neighbor, whom I really respect, won two awards. 
  • The polar bear, which is also known as the white bear, has very thick skin.
  • My brother, who left school at 10, works as a painter.
The non-defining relative clauses are sometimes used to comment on a whole clause. 
For example
My sister helped me with my assignment, which was kind.

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