auxiliary N5 essential casualpolitewritten

ない — plain negation and 'there isn't'

ない

Meaning

① plain negative: (do) not ~ — the plain-form negative of a verb or adjective

② 'there is not': there isn't ~ / don't have ~ — the negative of ある

① plain negative

今日きょうは学校がっこうに行いかない。

I'm not going to school today.

② 'there is not'

時間じかんがない。

There's no time.

Attaches to	Form	Example
Verb	negative base + ない (see ない形)	飲のむ → 飲のまない
i-adjective	〜い → 〜くない	高たかい → 高たかくない

When: Plain register; ない itself conjugates as an i-adjective (past なかった). The polite negative is 〜ません / 〜くないです.

① plain negative

肉にくは食たべない。

I don't eat meat.

この問題もんだいは難むずかしくない。

This problem isn't difficult.

i-adjective → 〜くない

② 'there is not'

今いま、お金かねがない。

I don't have money right now.

The negative of ある is the irregular standalone ない, never ×あらない. (For animate existence, いる → いない is regular.) 'there is not'

Jengo shows ない the way you actually meet it: inside real Japanese sentences, so it sticks instead of staying an abstract rule.

Sources Compiled with reference to A Dictionary of Intermediate Japanese Grammar.