definition of not by The Free Dictionary




A logical operator that returns a false value if the operand is true and a true value if the operand is false.




In no way; to no degree. Used to express negation, denial, refusal, or prohibition: I will not go. You may not have any.

[Middle English, alteration of naught, nought; see naught.]

Usage Note: The positioning of not and other negatives in a sentence is important to avoid ambiguity. The sentence All classes are not open to enrollment could be taken to mean either “All classes are closed to enrollment” or “Not all classes are open to enrollment.” Similarly, the sentence Kim didn’t sleep until noon could mean either “Kim went to sleep at noon” or “Kim got up before noon.” · Not only and but also are usually classified as correlative conjunctions. They add emphasis to each part of the construction and suggest that the second part is particularly unexpected or surprising. As with both … and and other correlatives, parallelism requires that each conjunction be followed by a construction of the same grammatical type. Thus, She not only bought a new car but also a new lawnmower displays faulty parallelism, where She bought not only a new car but also a new lawnmower does not, because both not only and but also are followed by noun phrases. See Usage Note at only.

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.





a. used to negate the sentence, phrase, or word that it modifies: I will not stand for it.

b. (in combination): they cannot go.

2. not that (conjunction) which is not to say or suppose that: I expect to lose the game — not that I mind. Also (archaic): not but what

sentence substitute

used to indicate denial, negation, or refusal: certainly not.

[C14 not, variant of nought nothing, from Old English nāwiht, from no + wiht creature, thing. See naught, nought]

Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014




1. (used to express negation, denial, refusal, prohibition, etc.): It’s not far from here. Are they coming or not? You must not think about it.

2. Slang. (used jocularly as a postpositive interjection to indicate that a previous statement is untrue): That’s a cute dress. Not!

[1275–1325; Middle English; weak variant of nought]



a Boolean operator that returns a positive result if its operand is negative and a negative result if its operand is positive.

Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.


Not is used with verbs to form negative sentences.

1. position of ‘not’

You put not after the first auxiliary verb or modal, if there is one.

They are not seen as major problems.

They might not even notice.

Adrina realised that she had not been listening to him.

If there is no other auxiliary verb, you use do as the auxiliary verb. After not you use the base form of a verb.

The girl did not answer.

He does not speak English very well.

In conversation, when not is used after be, have, do, or a modal, it is not usually pronounced in full. When you write down what someone says, you usually represent not as n’t and add it to the verb in front of it. In some cases, the verb also changes its form.

You nearly always use an auxiliary verb when you want to make a negative form of a verb using not. Don’t say, for example, ‘I not liked it‘ or ‘I liked not it‘. You say ‘I didn’t like it’.

There are two exceptions to this. When you use not with be, don’t use an auxiliary verb. You simply put not after be.

I‘m not sure about this.

The program was not a success.

When have is a main verb, not is sometimes added without an auxiliary verb, but only in the short forms hasn’t, haven’t, and hadn’t.

You haven’t any choice.

The sky hadn’t a cloud in it.

However, it is more common to use the forms doesn’t have, don’t have, and didn’t have.

This question doesn’t have a proper answer.

We don’t have any direct control of the prices.

I didn’t have a cheque book.

Be Careful!
When you use not to make what you are saying negative, you don’t usually use another negative word such as ‘nothing’, ‘never’, or ‘none’. Don’t say, for example, ‘I don’t know nothing about it‘. You say ‘I don’t know anything about it’.

2. ‘not really’

You can make a negative statement more polite or less strong by using really after not.

It doesn’t really matter.

I don’t really want to be part of it.

You can reply to some questions by saying ‘Not really‘.

3. ‘not very’

When you make a negative statement using not and an adjective, you can make the statement less strong by putting very in front of the adjective.

I’m not very interested in the subject.

That’s not a very good arrangement.

Be Careful!
Although you can say that something is not very good, don’t use ‘not’ in front of other words meaning ‘very good’. Don’t say, for example, that something is ‘not excellent‘ or ‘not marvellous‘.

4. used with to-infinitives

You can use not with a to-infinitive. You put not in front of to, not after it.

The Prime Minister has asked us not to discuss the issue publicly any more.

I decided not to go in.

5. ‘not’ in contrasts

You can use not to link two words or expressions. You do this to point out that something is the case, and to contrast it with what is not the case.

So they went by plane, not by car.

He is now an adult, not a child.

You can make a similar contrast by changing the order of the words or expressions. When you do this, you put not in front of the first word or expression and but in front of the second one.

This story is not about the past, but about the future.

He was caught, not by the police, but by a man who recognised him.

6. used with sentence adverbs

You can use not with surprisingly and unexpectedly to make a negative comment about a statement.

Laura, not surprisingly, disliked discussing the subject.

The great man had died, not unexpectedly and very quietly, in the night.

7. ‘not all’

Not is sometimes used with all and with words beginning with every- to form the subject of a sentence. For example, instead of saying ‘Some snakes are not poisonous’, you can say ‘Not all snakes are poisonous’.

Not all the houses have central heating.

Not everyone agrees with me.

8. ‘not only’

Not only is often used with but or but also to link two words or phrases.

9. ‘not’ in short replies

You can use not at the end of a short reply in order to give your opinion. For example, you can say ‘I hope not‘, ‘Probably not‘, or ‘Certainly not‘.

‘Will it happen again?’ – ‘I hope not.’

‘I hope she won’t die.’ – ‘Die? Certainly not!’

Collins COBUILD English Usage © HarperCollins Publishers 1992, 2004, 2011, 2012

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