not
1 Americanadverb
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(used to express negation, denial, refusal, or prohibition).
You must not do that. It's not far from here.
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U.S. Slang. (used jocularly as a postpositive interjection to indicate that a previous statement is untrue).
I just love working overtime without pay. Not!
idioms
noun
adverb
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used to negate the sentence, phrase, or word that it modifies
I will not stand for it
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( in combination )
they cannot go
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Also (archaic): not but what. (conjunction) which is not to say or suppose that
I expect to lose the game — not that I mind
combining form
Etymology
Origin of not
First recorded in 1275–1325; Middle English; weak variant of nought
Explanation
The adverb not is used for negation. Do you like drinking cod liver oil? No, I do not like drinking cod liver oil. Not is a powerful word. When Hamlet says "to be or not to be," he is questioning whether he should live or die, the inverse of living. Just be careful of what's called a "double negative," where you use not with another negating word and end up negating your negation. If you say you don't know nothing about something, that means you do know something. Not is often contracted as in don't, or isn't.
Vocabulary lists containing not
Spelling Practice, Unit 8
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Spelling Practice 1, Unit 3
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Higher exports from the U.S. have helped to offset—but not eliminate—the supply chasm created by the throttling of the Strait of Hormuz.
From The Wall Street Journal • Apr. 25, 2026
Whether or not it ever happens, the idea alone was so brash that the industry agreed that it could have come from only one person.
From The Wall Street Journal • Apr. 25, 2026
His route planners know not to let him in on splashy new destinations too far in advance.
From The Wall Street Journal • Apr. 25, 2026
Inherently compelling but also a shade predictable, the genre promises a tantalizing glimpse at a terrifyingly macho world — one that most of us are fortunate not to know firsthand.
From Los Angeles Times • Apr. 24, 2026
Messing up may be his thing, but not caring usually is, too.
From "Legendary Frybread Drive-In" by Cynthia Leitich Smith
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Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.