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 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

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 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

a Boolean operator with only one variable that has the value one when the variable is zero and vice versa

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