not S1 W1 /nɒt $ nɑːt/ adverb
[Date: 1300-1400; Origin: nought]

1. used to make a word, statement, or question negative:
Most of the stores do not open until 10 am.
She’s not a very nice person.
You were wrong not to inform the police.
‘Can we go to the park?’ ‘No, not today, dear.’
not at all/not ... at all (=used to emphasize what you are saying)
The changes were not at all surprising.
I do not like his attitude at all. ⇒ no¹, N’T

2. used in order to make a word or expression have the opposite meaning:
Edinburgh isn’t far now.
The food is not very good there.
not a lot/much/many etc (=only a few, only a little etc)
Not much is known about the disease.
Not many people have read the report.
Most of the hotels are not that cheap (=they are fairly expensive).

3. used instead of a whole phrase to mean the opposite of what has been mentioned before it:
No one knows if the story is true or not.
I hope to see you tomorrow, but if not, leave me a message.
‘Is Mark still sick?’ ‘I hope not.’ ⇒ so¹(4)

4. not only in addition to being or doing something
not only ... (but) also ...
Shakespeare was not only a writer but also an actor.
not only do/will/can etc
Not only do the nurses want a pay increase, they want reduced hours as well.

5. not a/not one not any person or thing:
Not one of the students knew the answer.
There wasn’t a cloud in the sky.
Not a single person said thank you.

6. not that ... used before a sentence or phrase to mean the opposite of what follows it, and to make the previous sentence seem less important:
Sarah has a new boyfriend – not that I care (=I do not care).
Janice had lost some weight, not that it mattered (=it did not matter).

7. not at all especially British English spoken used to be polite when someone has thanked you or asked you to do something:
‘Would you mind helping me with my suitcase?’ ‘Not at all.’

8. not the sharpest tool in the box/shed (also not the brightest crayon in the box), not the brightest bulb on the Christmas tree informal used to say that someone is not very intelligent or is not able to learn things quickly or easily – used humorously

9. –not! spoken used, especially by young people, to say that you really mean the opposite of what you have just said:
I really enjoy spending my day working here – not!
⇒ not half at half³(5), ⇒ not to say at say¹(44)


GRAMMAR
Do not use another negative word (eg 'no', 'nothing', 'nobody', 'never') with not. Use any, anything, anybody, ever etc:
They didn’t have any money (NOT didn’t have no money).
I didn’t know anybody (NOT didn’t know nobody).
When you use not with a to-infinitive, put it before the 'to':
I try not to make errors (NOT try to not make errors).

[TahlilGaran] Dictionary of Contemporary English ▲

not
adverb
BAD: He told me to not spend too long in the sun.
GOOD: He told me not to spend too long in the sun.

Usage Note:
Not and never usually go immediatley in front of a to infinitive:
'Try not to worry about anything.' 'It's hard not to feel sorry for him.'

[TahlilGaran] Dictionary of Common Errors ▲