～ない

～ない is the plain negative ending: “not”, “don't”, “isn't”. The ん in polite ～ません is this negative in disguise.

The same ない also negates i-adjectives (高くない = not expensive) and ～たい “want to” forms (行きたくない = don't want to go).

1. Plain negative of verbs

Attach ～ない to a verb to say the action does not (or will not) happen.

2. Polite negative ～ません

In polite speech the negative is ～ません. The final ん is the negative itself, riding on top of polite ます.

3. Negating adjectives ～くない

An i-adjective swaps its final い for く and takes ない: 高い → 高くない.

Negative ～ない vs standalone ない

Japanese also has a standalone, verb-like ない meaning “there is no ...” (the negative of ある): 時間がない = “there is no time”. That ない is a word on its own, not this negative ending attached to another word.

How to form it

Godan (u-verbs) shift the final syllable to the a-row and add ない: 書く → 書かない, 飲む → 飲まない; verbs ending in う use わ, so 買う → 買わない. Ichidan (ru-verbs) drop る and add ない. Irregulars: する → しない, 来る → 来ない. I-adjectives become ～くない. Polite speech uses ～ません, and the past negative is なかった.

• 書く（かく）= to write → 書かない（かかない）= don't write
• 買う（かう）= to buy → 買わない（かわない）= don't buy
• 食べる（たべる）= to eat → 食べない（たべない）= don't eat
• する = to do → しない = don't do
• 来る（くる）= to come → 来ない（こない）= don't come (special irregular verb)
• 高い（たかい）= expensive → 高くない（たかくない）= not expensive
• 行く（いく）= to go → 行きません（いきません）= don't go (polite)
• 食べない（たべない）= don't eat → 食べなかった（たべなかった）= didn't eat

Key idea

Once attached, ない behaves like an i-adjective itself, past なかった, te-form なくて. Japanese reuses one negative machine everywhere so learn its shapes once and you can negate anything.