aspect N4 common casualpolitewritten

なくなる — come to no longer ~

なくなる

Builds on ない形

Meaning

come to no longer ~ / stop ~ing — a change into a state where something is no longer so

最近さいきん、彼かれは学校がっこうに来こなくなった。

Lately he's stopped coming to school.

Attaches to	Form	Example
Verb (ない-form)	V-ない → V-なく + なる	食たべない → 食たべなくなる

年としを取とって、夜よるよく眠ねむれなくなった。

As I've gotten older, I've become unable to sleep well at night.

引ひっ越こしてから、彼女かのじょと会あわなくなった。

Since I moved, I no longer see her.

この道みちは工事こうじで通とおれなくなっている。

This road has become impassable due to construction.

Don't confuse this grammar with the lexical verb 無なくなる ('be used up / disappear', as in お金かねが無なくなった — the money ran out). The grammar here is ない + なる, attached to a verb or adjective.

Jengo shows なくなる 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 Basic Japanese Grammar.