not

adverb

• 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: [with infinitive]:he has been warned not to touch the pain of not knowing she not only wrote the text but also researched the photographs

• 2used 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

• 3used 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

• 4used 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
• informal humorous following and emphatically negating a statement:that sounds like quality entertainment—not

  [a usage popularized by the film Wayne's World]

noun

• 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.

adjective

• (of paper) not hot-pressed, and having a slightly textured surface.