What Is a Noun Clause?
A noun clause is a dependent clause that functions as a noun within a sentence. Just as a single noun can serve as the subject, object, or complement of a sentence, an entire clause — a group of words containing a subject and a verb — can fill the same role. Instead of saying "I know the answer," you can say "I know what the answer is." In both cases, the bold part functions as the object of the verb "know," but in the second sentence, it is a complete clause rather than a simple noun.
Noun clauses are essential building blocks of complex, sophisticated English. They allow us to express ideas that are too detailed or abstract for a single word or phrase. When you say "That she passed the exam surprised everyone," the noun clause "that she passed the exam" acts as the subject of the sentence — something no single noun could capture as precisely. Similarly, when you say "I wonder where he went," the clause "where he went" expresses a question embedded inside a statement.
Noun clauses are introduced by specific words called subordinators: that, whether/if, and all the wh-words (what, where, when, why, who, whom, whose, which, how). The subordinator you choose depends on the type of information the clause expresses — a fact, a question, or an uncertain situation. Mastering noun clauses is one of the most important steps toward writing and speaking English at an advanced level.
A noun clause answers the question "What?" about the main verb. If you can replace a clause with the word "something" or "it" and the sentence still makes grammatical sense, that clause is a noun clause.
Test: "I know what he said." → "I know something." ✔ (noun clause confirmed)
When Do We Use Noun Clauses?
Noun clauses appear in a wide variety of grammatical positions. Understanding the different roles they can play will help you use them naturally and accurately. The following table shows the main functions of noun clauses in English:
| Function | Explanation | Example |
|---|---|---|
| Subject | The noun clause acts as the subject of the sentence | What she said made everyone laugh. |
| Object of a verb | The noun clause acts as the direct object | I believe that honesty is important. |
| Object of a preposition | The noun clause follows a preposition | We talked about what happened yesterday. |
| Subject complement | The noun clause follows a linking verb (be, seem, appear) | The problem is that we do not have enough time. |
| After adjectives | Some adjectives require a noun clause to complete their meaning | I am glad that you could come. |
| In apposition | The noun clause renames or explains a noun before it | The fact that the Earth is round was once controversial. |
Certain verbs are commonly followed by noun clauses. These include: know, think, believe, hope, wish, assume, realize, understand, notice, discover, explain, suggest, recommend, decide, wonder, doubt, imagine, suppose, expect, feel, fear, guess, hear, learn, remember, forget, agree, admit, claim, deny, mention, prove, reveal, show. Memorizing this list will help you recognize and construct noun clauses naturally.
That-Clauses
The most common type of noun clause is introduced by the subordinator that. A that-clause expresses a statement or a fact. It follows the normal word order of a declarative sentence (subject + verb) and is used after reporting verbs, opinion verbs, and adjectives that express feelings or judgements.
that + subject + verb + (rest of clause)
The word "that" can often be omitted in informal English when the clause functions as an object, but it must be kept when the clause functions as a subject or comes after certain expressions.
| Position | Example with "That" | "That" Omissible? |
|---|---|---|
| Object | I think (that) she is right. | Yes — very common in speech |
| Object (after reporting verb) | He said (that) he would be late. | Yes — frequently omitted |
| Subject | That he lied was obvious to everyone. | No — "that" is required |
| After "the fact" | The fact that she arrived early impressed us. | No — "that" is required |
| After adjective | I am certain (that) this is correct. | Yes — in informal contexts |
| Subject complement | The truth is that nobody knows the answer. | Usually kept for clarity |
When a that-clause acts as the subject of a sentence, it can sound heavy and formal. In everyday English, we often use "It" as a dummy subject and move the clause to the end:
That he refused the offer was surprising. (formal, grammatically correct but heavy)
It was surprising that he refused the offer. (natural, preferred in most contexts)
Whether / If Clauses
When a noun clause expresses uncertainty, a choice, or a yes/no question embedded in a statement, it is introduced by whether or if. These clauses are used after verbs and expressions that involve doubt, uncertainty, or indirect questions. The critical point to remember is that inside the clause, you must use statement word order (subject + verb), not question word order.
whether / if + subject + verb + (rest of clause)
Whether and if are interchangeable in many cases, but whether is preferred in formal writing, after prepositions, before infinitives, and when the clause is in the subject position.
| Context | Whether | If |
|---|---|---|
| After verbs of uncertainty | I wonder whether she will come. | I wonder if she will come. |
| As subject | Whether he agrees is not important. | ✘ If he agrees is not important. |
| After prepositions | It depends on whether we have time. | ✘ It depends on if we have time. |
| Before infinitives | I cannot decide whether to go or stay. | ✘ I cannot decide if to go or stay. |
| With "or not" (immediately after) | I do not know whether or not he is coming. | ✘ I do not know if or not he is coming. |
| With "or not" (at the end) | I do not know whether he is coming or not. | I do not know if he is coming or not. |
Do not confuse "if" in noun clauses (meaning "whether") with "if" in conditional sentences (meaning "in the case that"):
I do not know if he is coming. (noun clause = whether)
If he comes, I will tell him. (conditional = in the case that)
The easiest test: try replacing "if" with "whether." If the meaning stays the same, it is a noun clause.
Wh- Clauses (Question Word Clauses)
When a noun clause is based on a question word — what, where, when, why, who, whom, whose, which, or how — it is called a wh-clause. These clauses embed a question inside a statement, and the most important rule is that they use statement word order, not question word order. This means the subject comes before the verb, and no auxiliary verb is added.
wh-word + subject + verb + (rest of clause)
The wh-word serves as the subordinator that connects the clause to the main sentence. Inside the clause, the order is always subject + verb, never the inverted question form.
| Direct Question | Noun Clause (Statement Order) |
|---|---|
| Where does she live? | I know where she lives. |
| What time did the meeting start? | Can you tell me what time the meeting started? |
| Why is he angry? | I do not understand why he is angry. |
| Who wrote this poem? | Nobody knows who wrote this poem. |
| How much does it cost? | Please tell me how much it costs. |
| When will they arrive? | I wonder when they will arrive. |
| Which one should I choose? | I cannot decide which one I should choose. |
| Whose jacket is this? | Do you know whose jacket this is? |
Many learners keep the question word order inside noun clauses. This is the single most frequent error with this topic.
✘ I do not know where does she live.
✔ I do not know where she lives.
✘ Can you tell me what time does the train leave?
✔ Can you tell me what time the train leaves?
Remember: the moment a question becomes part of a larger sentence, it loses its question structure.
When who or what is the subject of the clause (not the object), the word order looks the same as a direct question because there is no inversion needed:
Direct question: Who called you? → Noun clause: I know who called you.
The word order is identical because "who" is already in the subject position.
Special Patterns and Rules
Noun clauses have several special patterns that go beyond the basic formulas. These advanced structures appear frequently in formal writing, academic contexts, and standardized examinations. Understanding them will elevate your command of complex English.
| Pattern | Explanation | Example |
|---|---|---|
| It + be + adjective + that | Dummy "it" as subject, noun clause at end | It is obvious that he was lying. |
| It + be + noun + that | Dummy "it" with a noun complement | It is a shame that you missed the concert. |
| Subjunctive after suggest/recommend | After verbs of suggestion, demand, or insistence, use the base form of the verb | The doctor suggested that he take a day off. |
| Subjunctive after it is important that | After expressions of necessity, use the base form | It is essential that every student be on time. |
| Whatever / Whoever / Wherever | Compound wh-words introduce noun clauses meaning "anything that" or "anyone who" | Whatever you decide is fine with me. |
| Wh-word + infinitive | A condensed form of a noun clause using an infinitive | I do not know what to say. (= what I should say) |
| The fact that | Used to give extra weight to a that-clause, especially after prepositions | I am impressed by the fact that she speaks five languages. |
After verbs like suggest, recommend, insist, demand, request, propose, require, and after expressions like it is important/essential/vital that, use the base form of the verb in the noun clause, regardless of the subject:
✔ She insisted that he be present. (not "is" or "was")
✔ They recommended that she apply immediately. (not "applies")
This is the English subjunctive mood, and it is frequently tested in exams.
Many noun clauses with wh-words can be condensed using an infinitive. This shorter form implies a meaning of "should" or "can":
"I do not know what I should do." → "I do not know what to do."
"She showed us how we could make pasta." → "She showed us how to make pasta."
This pattern works with what, where, when, how, which, and whether (but not why or who).
A noun clause is a thought captured inside a sentence — proof that language is rich enough to hold one idea inside another, and still make perfect sense.
— The Grammar GazetteExample Sentences
Noun Clauses with Reporting Verbs
Noun clauses are essential in reported speech. When we report what someone said, asked, or thought, we use noun clauses as the objects of reporting verbs. The choice of subordinator depends on the type of original statement: that for statements, whether/if for yes/no questions, and wh-words for information questions.
| Original | Reporting Verb | Reported with Noun Clause |
|---|---|---|
| "I love this city." | said | She said that she loved that city. |
| "Are you coming?" | asked | He asked whether I was coming. |
| "Where is the station?" | wanted to know | She wanted to know where the station was. |
| "I will finish it tomorrow." | promised | He promised that he would finish it the next day. |
| "Who broke the window?" | wanted to find out | The teacher wanted to find out who had broken the window. |
| "You should see a doctor." | suggested | My friend suggested that I should see a doctor. |
Statement verbs: say, tell, mention, explain, announce, claim, admit, deny, state, report, add, reply, answer, promise, warn, remind, inform
Question verbs: ask, wonder, inquire, want to know, need to find out
Suggestion verbs: suggest, recommend, propose, advise, insist, demand, request, urge
When the reporting verb is in the past tense, the tenses inside the noun clause usually shift back: present → past, past → past perfect, will → would, can → could. However, this shift is optional when the information is still true at the time of reporting:
He said that the Earth revolves around the Sun. (still true — no shift needed)
Common Mistakes
Noun clauses present several challenges for learners. Here are the most frequent errors and clear guidance on how to avoid them:
The number one error is keeping the inverted question form inside a noun clause.
✘ I do not know what is his name.
✔ I do not know what his name is.
✘ Tell me where did you go.
✔ Tell me where you went.
In direct questions, we use auxiliary verbs like do, does, did. In noun clauses, these auxiliaries disappear.
✘ She asked me where did I work.
✔ She asked me where I worked.
✘ I wonder what does she want.
✔ I wonder what she wants.
✘ If he comes or not does not matter.
✔ Whether he comes or not does not matter.
✘ It depends on if the weather improves.
✔ It depends on whether the weather improves.
After verbs of suggestion and necessity, use the base form — not the conjugated form.
✘ He suggested that she goes home early.
✔ He suggested that she go home early.
✘ It is vital that every student is present.
✔ It is vital that every student be present.
A noun clause functions as a noun (subject or object). A relative clause modifies a noun.
What he said was true. (noun clause = subject of the sentence)
The thing that he said was true. (relative clause = modifies "thing")
If you can replace the clause with "something" or "it," it is a noun clause.
Quick Reference Summary
Use this comprehensive comparison table to review the three main types of noun clauses and their key characteristics at a glance:
| Type | Introduced By | Function | Word Order | Example |
|---|---|---|---|---|
| That-clause | that (often omissible) | States a fact or belief | that + S + V | I know that she is right. |
| Whether/If clause | whether, if | Expresses uncertainty or yes/no | whether/if + S + V | I wonder whether it will rain. |
| Wh-clause | what, where, when, why, who, how, etc. | Embeds an information question | wh-word + S + V | Tell me where you live. |
| Wh- + infinitive | what to, how to, where to, etc. | Condensed form (= should/can) | wh-word + to + V | I know how to fix it. |
| Whatever / Whoever | whatever, whoever, wherever, etc. | Means "anything/anyone that" | compound wh- + S + V | Whatever you want is fine. |
No matter which type of noun clause you use, always remember the Statement Word Order rule: inside a noun clause, the subject comes before the verb. There is no inversion, no auxiliary "do/does/did" added. This single rule will prevent the majority of mistakes learners make with noun clauses. When in doubt, find the subject and the verb inside the clause and make sure they are in S + V order.
Noun clauses are the bridge between simple and complex English. They allow you to report speech, express opinions, embed questions, and discuss abstract ideas with precision and clarity. Practice converting direct questions into noun clauses, and pay close attention to word order. With consistent practice, using noun clauses will become as natural as using single nouns.
Think you've mastered Noun Clauses? Put your knowledge to the test with our interactive quiz featuring 25 carefully crafted questions.
Take the Quiz