The difference between 'Don't do something' and 'Not do something'

For example, as following scene:

A: I want to buy toy?

B: Don't buy toy!

Could I just say not buy toy?

There are any difference between those two sentences? And can I use one replace the other?

2 Answers 2


Don't (do not) do something is an imperative. It is a complete sentence. You are telling someone what they should not do.

Not do something is a sentence fragment. It is not a full sentence. You need more information. Is a person currently not doing something? Are they doing something they should not be doing, or are they not doing something they should be doing? Is it not possible for them to do the thing? And so on.

  • If I don't want a stuff, I just say not it, and don't need to say it isn't it, likewise, not interested and I am not interested. are these all grammar analogous?
    – yixuan
    Apr 2, 2021 at 15:02
  • 3
    @yixuan If someone offers you something and you don't want it, I am not interested is a correct response. Not interested is not proper written English but it's an understandable shortening of I am not interested and is fine in spoken English. Not it and it isn't it make no sense in this context, written or spoken.
    – randomhead
    Apr 2, 2021 at 15:26

Q. The difference between 'Don't do something' and 'Not do something'

First lets put both these sentences into BASIC English.

'Don't do something' = Do not (to) do something

'Not do something' = Not (to) do something

Do not do something in this case, I believe the FIRST "do" which is an auxiliary verb is added to emphasis the point of "not doing". However it is commonly used with another verb to form questions and negative sentences.

do auxiliary verb (FOR EMPHASIS)[ + infinitive without to ] used to give extra force to the main verb:C.E.D. It is also used with another verb to form questions and negative sentences, including negative orders.

The second "do" of "do something" is a full verb used meaning to perform, take part in, or achieve something

The verb do can be both an auxiliary and a full verb. As an auxiliary we use do in negative sentences and questions for most verbs

So we have a short, stand-a-lone, emphasised negative command. A sentence that forms a command is known as an imperative sentence.

The imperative mood is one of the four main verb moods in the English language. As opposed to verb tenses, which indicate time, moods indicate states. The imperative mood indicates the state of commanding.Grammarly

** Obviously the phrase not do something has the same meaning as in the first sentence (but without the emphasis) However, it must be used in context it does not work as a stand alone statement. It also may or may not form an imperative sentence.

Answer. Therefore the two examples are not interchangeable and the second cannot be used as a stand-a-lone sentence. Finally the mood of the phrase may or may not be the same depending on context.

I will not do the washing today, as they have forecast rain later.

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