not

Từ điển Oxford Advanced Learner 8th

not BrE [nɒt] NAmE [nɑːt] adverb
1. used to form the negative of the verbs be, do and have and modal verbs like can or must and often reduced to n't
•She did not/didn't see him.
•It's not/It isn't raining.
• I can't see from here.
• He must not go.
•Don't you eat meat?
•It's cold, isn't it?
2. used to give the following word or phrase a negative meaning, or to reply in the negative
• He warned me not to be late.
• I was sorry not to have seen them.
•Not everybody agrees.
•‘Who's next?’ ‘Not me.’
•‘What did you do at school?’ ‘ Not a lot.’
•It's not easy being a parent (= it's difficult).
3. used after hope, expect, believe, etc. to give a negative reply
• ‘Will she be there?’ ‘I hope not.’
• ‘Is it ready?’ ‘I'm afraid not.’
• (formal)‘Does he know?’ ‘I believe not.’
4. or ~ used to show a negative possibility
• I don't know if he's telling the truth or not.
5. used to say that you do not want sth or will not allow sth
• ‘Some more?’ ‘Not for me, thanks.’
• ‘Can I throw this out?’ ‘Certainly not.’
Idioms: ↑not a … ▪ ↑not at all ▪ ↑not one … ▪ ↑not only … also … ▪ ↑not that

Word Origin:
[not] Middle English: contraction of the adverb ↑nought.