not / nät/ • adv. 1. (also n't joined to a preceding verb) used with an auxiliary verb or “be” to form the negative: he would not say | she isn't there | didn't you tell me? ∎  used in some constructions with other verbs: he has been warned not to touch the pain of not knowing | she not only wrote the text but also researched the photographs. 2. used as a short substitute for a negative clause: maybe I'll regret it, but I hope not | “Don't you keep in touch?” “I'm afraid not.” | they wouldn't know if I was telling the truth or not.3. used to express the negative of other words: not a single attempt was made | treating the symptoms and not the cause | “How was it?” “Not so bad.” ∎  used with a quantifier to exclude a person or part of a group: not all the poems are serious. ∎  less than (used to indicate a surprisingly small quantity): the brakes went on not ten feet from him.4. used in understatements to suggest that the opposite of a following word or phrase is true: the not too distant future | not a million miles away. ∎ inf., humorous following and emphatically negating a statement: that sounds like quality entertainment—not.• n. (often NOT) Electr. a Boolean operator with only one variable that has the value one when the variable is zero and vice versa. ∎  (also not gate) a circuit that produces an output signal only when there is not a signal on its input.• adj. (often Not) Art (of paper) not hot-pressed, and having a slightly textured surface.PHRASES: not at all1. used as a polite response to thanks.2. definitely not: “You don't mind?” “Not at all.”not but what archaic nevertheless: not but what the picture has its darker side.not half see half.not least see least.not quite see quite.not that it is not to be inferred that: I'll never be allowed back—not that I'd want to go back.not a thing nothing at all.not very see very.