A noun clause is a type of subordinate clause. A noun clause does the same work as a noun in a sentence. It is different from a noun phrase because it has a finite verb, and a subject.

A noun clause can be replaced by “she/he/it” or “that/those/them”. Examples:

The news that I heard last night gave me a big shock. (The noun clause is “The news I heard last night”. You can also say: “It gave me a big shock” or “That gave me a big shock”.)

I find it hard to believe that it’s almost the end of the year. The noun clause is “That it’s almost the end of the year”. You can also say: I find that hard to believe.

You can also ask the question “who?” or “what?” to find the noun clause. A noun clause can be the subject or object of a sentence. Examples:

People who eat too much sugar may get an illness called diabetes later in life. (Who may get an illness called diabetes later in life? People who eat too much sugar. This answer is the subordinate noun clause. It is the subject of the sentence.Notice that you can replace the clause with ‘they’, as in: They may get an illness called diabetes later in life.

The reasons that he gives for always being absent are weak. (What are weak? The reasons he gives for always being absent. This answer is the subordinate noun clause. It is the subject of the sentence. Again, you can replace it with ‘they’, as in: They are weak.

We should always think about why we choose to do certain things. (What should we think about? Why we choose to do certain things. The answer is the subordinate noun clause. It is the object of the sentence. Notice you can replace the clause here with ‘it’, as in, We should think about it

I wonder how long Mpethi will be. (What do I wonder? How long Mpethi will be. The answer is the noun clause. It is the object of the sentence.)

(A noun clause is always a subordinate clause, because the main clause of a sentence is the one that has the main verb, and so is not playing the role of a noun.)