Noun Clauses
Learn how an entire clause can act as a noun, which words introduce it, and the different positions it can fill within a sentence.
Acting as a noun
A noun clause does the job a single noun would do.
A noun clause is a dependent clause that functions as a noun. It can fill the subject, object or complement position in a sentence, the same positions a single noun or pronoun could fill.
In What she said surprised everyone., the clause what she said acts as the subject of the sentence. Compare this to Her comment surprised everyone., where the single noun comment fills the same position.
Several words can introduce a noun clause, and the clause can fill more than one position within a sentence.
Before you begin
Noun clauses are one of five clause types.
This lesson focuses on noun clauses specifically. Clauses as a whole include four other types, each covered in its own lesson.
If you would like an overview of how clauses work in general, begin with the Clauses page.
The central idea
A clause can fill exactly the same position as a single noun.
Compare a sentence with a single noun to the same sentence with a noun clause instead.
01
Single noun
Her comment surprised everyone.
02
Noun clause
What she said surprised everyone.
The useful question is: could a single noun replace this clause?
Both her comment and what she said occupy the subject position and are followed by the same verb, surprised. If a clause can be swapped for a single noun this way, it is functioning as a noun clause.
Words that introduce a noun clause
Several words can open a noun clause.
that → She said that she was tired.
what → What she said surprised everyone.
whether / if → I don’t know whether she called.
who / whoever → Whoever arrives first can choose the seat.
where / when / why / how → I wonder where she went.
The jobs a noun clause can do
A noun clause can fill several positions in a sentence.
As the subject
What she said surprised everyone.
As the object of a verb
I know that she is tired.
As a subject complement
The problem is that we are out of time.
Here, the clause follows the verb is and renames the subject, the problem.
As the object of a preposition
She was interested in what he had to say.
A connection to indirect questions
A noun clause introduced by a question word works like an embedded question.
Do you know where she went?
A noun clause opened by if, whether, or a question word such as where, uses statement word order rather than the inversion a direct question would use. This pattern is covered in more depth in the Indirect Questions lesson.
A useful decision guide
Ask what position the clause fills, and whether a noun could replace it.
01
Could a single noun or pronoun replace this clause?
If so, the clause is likely functioning as a noun.
02
What position does the clause fill?
Check whether it is the subject, an object, or a complement.
03
Does the clause open with a question word?
If so, it should keep statement word order, not question order.
04
Is the clause describing a noun already named, rather than acting as one?
If so, it is a relative clause instead, not a noun clause.
Common mistakes
A noun clause keeps statement word order, even when it starts with a question word.
The subject and verb should not invert inside the clause.
Not: I don’t know where does she live.
Correct: I don’t know where she lives.
Once where she lives functions as a noun clause, it follows statement order, not question order.
A noun clause is not confused with a relative clause.
Relative clause: the book that I read (describes the noun “book”)
Noun clause: what I read (acts as the noun itself)
A relative clause attaches to a noun already stated; a noun clause takes the place of the noun entirely.
A yes/no idea needs if or whether once it is a noun clause.
Not: I don’t know she called.
Correct: I don’t know if she called.
Check your understanding
What position does the noun clause fill?
Choose the correct answer for each sentence.
What she decided affected the whole team.
✅ Exactly! What she decided is doing the affecting, so it is the subject.
❎ Not quite. Ask what is performing the action of the verb, affected.
What came before the verb “affected”?
She believes that the plan will succeed.
✅ Exactly! That the plan will succeed is what she believes, so it is the object of the verb believes.
❎ Not quite. Ask what “she” is the subject of, and what follows the verb.
Who or what already fills the subject position here?
“the book that I read” — is “that I read” a relative clause or a noun clause?
✅ Exactly! It describes the noun “book” that is already stated, so it is a relative clause, not a noun clause.
❎ Not quite. Does this clause replace a noun, or describe one already named?
Compare this to “what I read”, without the noun “book”.
Choose the best explanation
Select the sentence that explains the noun clause correctly.
Why is “I don’t know where does she live.” not correctly formed?
✅ Exactly! A noun clause uses statement word order, even when introduced by a question word.
❎ Not quite. This sentence already has a question word, “where”.
What distinguishes “the book that I read” from “what I read”?
✅ Exactly! This is the key difference between a relative clause and a noun clause.
❎ Not quite. Compare whether a noun, “book”, is stated separately in each version.
Try it another way
Complete each sentence with a noun clause.
Type the missing word.
✅ Exactly! That introduces this noun clause as the object of “explained”.
❎ Not quite. Think about the word that commonly introduces a noun clause like this one.
✅ Exactly! Whoever finishes first acts as the subject of the sentence.
❎ Not quite. This word should refer to an unspecified person, and act as the subject.
Quick review
A noun clause fills the same positions a single noun could fill.
A noun clause is a dependent clause that functions as a noun.
Words such as that, what, whether, if, and question words like where or why can introduce a noun clause.
A noun clause can act as the subject, the object, a subject complement, or the object of a preposition.
A noun clause keeps statement word order, even when it opens with a question word.
A noun clause replaces a noun entirely; a relative clause describes a noun that is already stated.
Remember
Ask whether a single noun could take the clause’s place.
If a noun or pronoun could be swapped in without changing the sentence’s structure, the clause is functioning as a noun, wherever in the sentence it appears.