んじゃないDon't, Mustn't, Shouldn't have

んじゃない is a slightly slang grammar pattern used with verbs to prohibit or request that something not be done. It will usually just be translated as 'don't do (A)', or 'you mustn't (A)'. んじゃない is almost always used from a higher position toward someone of a lower status. It may be used when the speaker is angry, but not always.

んじゃない is a combination of the case-marking particle の, and the abbreviated form of ではない, じゃない. It will connect to the dictionary form of verbs.

Despite being slang, the slightly more formal version んじゃありません can also be seen occasionally. This variation is common when the speaker wants to forbid something, but not sound angry, such as when an adult is talking to a child.

The more literal translation of Verb + んじゃない is just 'it's not (verb)'. This sounds a bit strange in English, but might be similar to something like 'you're not (verb)', where a person is directly telling another what they shouldn't do.

It is also common to see the abbreviated ている form, てん, before じゃない.

Caution

When used in the past tense, んじゃなかった indicates that something 'should not have been done', and has a nuance of regret or disappointment that the action occurred.

Caution

When んじゃない comes at the end of a sentence, it will be important to listen to the intonation, as the statement may actually be a question. In this case, it is an abbreviation of んじゃないか.

The difference between these two uses of んじゃない will usually be very clear. A question has a rising intonation, while an order will have a dropping intonation.