This is the 5967th most frequent Japanese word.
んじゃ
"んじゃ" is a casual contraction in Japanese meaning "well then" or "in that case."
In this sentence, 'んじゃない' is used as an abbreviated form of 'のではない', which negates the action or state. It creates a directive tone, indicating prohibition.
それをやるんじゃない、と先生が言った。
The teacher said, 'Don't do that.'
Here, 'んじゃないか' expresses assumption or speculation. It's used conversationally to suggest a possibility or expectation.
彼が来るんじゃないかと思った。
I thought he might come.
In this context, 'んじゃない' implies a negative comment on an event or situation, derived from 'のではない', suggesting a state of non-commencement.