じゃない

expression

isn't; is not (informal); isn't it?

1. is not; isn't (informal negative copula)

Casual contraction of ではない, the negative form of the copula だ/である. Attaches to a noun or na-adjective to express 'X is not Y'.

それは私(わたし)のじゃない。

That's not mine.

彼(かれ)は学生(がくせい)じゃない。

He isn't a student.

昨日(きのう)言(い)ったことは本当(ほんとう)じゃないと思(おも)う。

I don't think what you said yesterday is true.

2. isn't it?; right? (tag question)

With rising or emphatic intonation, expresses confirmation, surprise, or mild disagreement — 'isn't it!', 'don't you think?'. Similar to a tag question in English.

いいじゃない！

That's nice, isn't it!

それでいいんじゃない？

Isn't that fine the way it is?

あの店(みせ)、結構(けっこう)美味(おい)しかったじゃない。

That restaurant was actually pretty good, wasn't it.

Casual contraction of ではない. The default informal negative copula in everyday speech.

Forms by politeness

Plain: じゃない
Plain past: じゃなかった
Polite: じゃないです / じゃありません
Formal: ではない / ではありません

Attachment

Noun + じゃない: 学生(がくせい)じゃない (not a student)
Na-adjective + じゃない: 元気(げんき)じゃない (not well)
Cannot attach directly to i-adjectives or verbs — those have their own ない negatives (高(たか)くない, 行(い)かない).

SENSE 2 — TAG QUESTION:
With rising or emphatic intonation, じゃない seeks agreement or expresses mild surprise. Often follows the explanatory ん: いいんじゃない？ ('isn't that okay?'). Without the question mark, the same construction can express positive evaluation: いいじゃない！ ('that's great, isn't it!').

Similar words

ではない: more formal written form
じゃありません: polite negative
じゃん: even more casual confirmation tag (Kanto dialect, now widespread)

Related Words

Related: じゃん (isn't it (casual, Kanto))

general

Added 2026.5.31 13:10 · Revised 2026.9.2 13:02

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