なかった Form — Plain Past Negative
The plain (casual) past negative — "did not ~". Used among friends or in plain writing; functionally equivalent to the polite ませんでした.
Structure
[ない form] → drop the final い + かった
Examples
あの本は読まなかった。
Ano hon wa yomanakatta.
I didn't read that book.
読まない → drop い → 読まなかった.
昨日は来なかったね。
Kinou wa konakatta ne.
You didn't come yesterday, did you?
来る is irregular: negative is こない (konai) → こなかった.
日曜日は勉強しなかった。
Nichiyoubi wa benkyou shinakatta.
I didn't study on Sunday.
勉強しない → drop い → 勉強しなかった (plain past negative).
• い-Adjective Logic: the plain negative (〜ない) behaves like an い-adjective, so it forms the past by い→かった — exactly like an い-adjective (高い→高かった). • Stacking: this logic chains — 食べたくない (don't want to eat) → 食べたくなかった (didn't want to eat).
Commonly confused with
The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones なかった is tested against.
vs ませんでした (polite past negative)
なかった is plain/casual; ませんでした is polite. 読まなかった vs 読みませんでした — same meaning, different register.
More verb forms
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