The Comma and Adjective Clauses

First Published: 20th of January, 2021

An adjective clause does one of two things in a sentence:

1. Defines a noun.
2. Gives more information about a noun.

When an adjective clause defines a noun, separate it with a comma, but when an adjective clause simply gives more information about a noun, do not separate it with a comma.

Here is an example:

The cap which I wore to the football match has been stolen.

The adjective clause “which I wore to the football match” defines the cap. That is because, in this context, I have several caps, and I want the reader to understand which cap exactly I’m referring to. An adjective clause which defines a noun is called an essential adjective clause. Do not separate an essential adjective clause with a comma.

Let’s look at another example:

An American, whom I met at the Takutu Hotel, gave me this book.

In the above example, the adjective clause, “whom I met at the Takutu Hotel,” is not essential to the meaning of the sentence. It simply adds more information about the noun, American. It is called a non-essential adjective clause. Always separate non-essential adjective clauses with a comma.

Here is another example:

The Canadian whom I met at the Takutu Hotel gave me this compass.

In the above sentence, I did not separate the adjective clause, “whom I met at the Takutu Hotel,” with a comma because it is used as an essential clause. That is, I want you to understand that the Canadian “whom I met at the Takutu Hotel” gave me the compass, and not, for example, the Canadian “whom I met at Ori Hotel.” In this context, I am using the adjective clause to define the Canadian, so it is treated as an essential adjective clause.

But I could also write:

The Canadian, whom I met at the Takutu Hotel, gave me this compass.

In the above sentence, I used the same clause again, but this time, as a non-essential adjective clause. That is, I did not use the adjective clause to define the noun, but simply to add more information about the noun. In this context, it is understood that I only met one Canadian so there is no need to distinguish him. Therefore, the adjective clause simply gives more information. It is called a non-essential adjective clause.

The same adjective clause can be used as an essential or non-essential adjective clause: depending on how you intend it. And you see, above, one such example.