在英语语法中，名词从句是一种从属从句，在句子中充当名词（即主语、宾语或补语）。也称为名词性从句。

英语中两种常见的名词从句是that从句和wh从句：

• 我相信每件事的发生都是有原因的。
• 我怎么知道我在想什么，直到我明白我在说什么？

名词从句的实例与观察

"When Mrs. Frederick C. Little's second son arrived, everybody noticed that he was not much bigger than a mouse." — E.B. White, Stuart Little, 1945 "What I like doing most of all in the evenings, these days, is sitting in a gormless stupor in front of the television, eating chocolate." — Jeremy Clarkson, The World According to Clarkson. Penguin Books, 2005 "A university is what a college becomes when the faculty loses interest in students." — John Ciardi, Saturday Review, 1966 "I know that there are things that never have been funny, and never will be. And I know that ridicule may be a shield, but it is not a weapon." — Dorothy Parker "I believe that there is a subtle magnetism in Nature, which, if we unconsciously yield to it, will direct us aright." — Henry David Thoreau, "Walking" "The thought of stars contributed to the power of his feeling. What moved him was a sense of those worlds around us, our knowledge however imperfect of their nature, our sense of their possessing some grain of our past and of our lives to come." — John Cheever, Oh What a Paradise It Seems. Random House, 1982 "Whoever was the person behind Stonehenge was one dickens of a motivator, I'll tell you that." — Bill Bryson, Notes From a Small Island. Doubleday, 1995 "How we remember, what we remember, and why we remember form the most personal map of our individuality." — Christina Baldwin "How people knew when they were being trailed he found himself unable to imagine." — Edmund Crispin [Robert Bruce Montgomery], Holy Disorders, 1945 "This is the story of what a Woman's patience can endure, and of what a Man's resolution can achieve." — Wilkie Collins, The Woman in White, 1859 "I knew exactly how clouds drifted on a July afternoon, what rain tasted like, how ladybugs preened and caterpillars rippled, what it felt like to sit inside a bush.” — Bill Bryson, The Life and Times of the Thunderbolt Kid. Broadway Books, 2006 "That dogs, low-comedy confederates of small children and ragged bachelors, should have turned into an emblem of having made it to the middle class—like the hibachi, like golf clubs and a second car—seems at the very least incongruous." — Edward Hoagland, "Dogs, and the Tug of Life"

作为直接宾语的名词性从句

"All sentences, then, are clauses, but not all clauses are sentences. In the following sentences, for example, the direct object slot contains a clause rather than a noun phrase. These are examples of nominal clauses (sometimes called 'noun clauses'):​ I know that the students studied their assignment. I wonder what is making Tracy so unhappy. These nominal clauses are examples of dependent clauses—in contrast to independent clauses, those clauses that function as complete sentences." — Martha Kolln and Robert Funk, Understanding English Grammar, 5th ed., Allyn and Bacon, 1998 "A Colorado study found that the average homeless person cost the state forty-three thousand dollars a year, while housing that person would cost just seventeen thousand dollars." — James Surowiecki, "Home Free?" The New Yorker, September 22, 2014

名词从句起始语

"We use various words to start noun clauses. ... "These words include the word that, which in its role as a noun clause starter is not a relative pronoun, for it serves no grammatical role in the clause; it just starts the clause. For example: The committee stated that it would follow the agent's policy. Here the noun clause serves the noun role of direct object of the transitive verb stated. But a careful look at the clause reveals that the word that does not serve any role within the clause, other than simply to get it going. "Other noun clause starters do serve grammatical roles within the clause. For example: We know who caused all the trouble. Here the noun clause starter is the relative pronoun who. Notice that inside the noun clause who serves as the grammatical subject of the verb caused. "Additional words serve as noun clause starters. A relative adverb can get one going: How he won the election mystified the pundits. So can a relative pronoun acting as an adjective: We know which career she will pursue. In these two sentences, how is an adverb modifying the verb won, and which is a relative-pronoun-adjective modifying the noun career." — C. Edward Good, A Grammar Book for You and I—Oops, Me! Capital Books, 2002 "I have run, I have crawled, I have scaled these city walls, These city walls Only to be with you, Only to be with you. But I still haven't found what I'm looking for." — written and performed by U2, "I Still Haven't Found What I'm Looking For." The Joshua Tree, 1987