grammar link

  1. ない (無い), which loosely means “does not exist” for non-living (or more accurately “non-breathing”) things, can be treated like an adjective. Therefore, conjugate it into an adverbial form of なく to talk about a change of state (なる). なくなる then means roughly that something will “begin to stop existing” (i.e. lost or disappeared). In other words, ある ‘becomes’ ない. Let’s look at few specific examples to make this clear:

    お金がなくなった [I lost my money]
    本がなくなった [I lost my book]

    The …くなる construction is something you will hear a lot.
    寒くなる to get cold
    無くなる to get lost (lit. to become not here)
    小さくなる to get smaller (basically synonymous with 縮む)

  2. We can use this same pattern for *any* negative word, including verbs. This basically means to stop doing something.

    もう気にしなくなった [I stopped caring]
    宝くじに当たって仕事をしなくなりました [I won the lottery and quit work]
    暖かくなくなる [to get not warm]

    Grammar link |なる、する
    見えなくなる: to be/become not seen; (見える-to be seen)

    For opposite, use [見える] + ように+なる: 見えるようになる – to become visible/seen

    (The grammatical opposite of 見えなくなる would be 見えるようになる (raw verb needs ように unlike the negative has adjective-adverb conjugation), but it’s more strongly associated with the other meaning of 見える, “able to see”. It’s also natural to use 見えるようになる in the setting “come within the scope of sight” (e.g. 夏の星座が見えるようになる), but for fading and emerging kind of visibility change, you could instead use 現れる “appear” or 出てくる “pop up” etc.)

  3. じゃない(ではない)contains ない, and the “+なくなる” pattern can be used here as well to good effect.

    いつか素人じゃなくなるよ [Some day you won’t be a amateur anymore]
    このサイトはもうただじゃなくなった [This web site isn’t free anymore]

  4. “しなければいけない” expression (“have to do”).

    会社を止めなければいけなくなったらどうするの? [If you had to quit your company what would you do?]

  5. when you become confused about something.

    よく分からなくなった [I’m confused]
    Literally this means “(I) stopped understanding well”, but the English “I’m confused” captures this nuance in a more natural way.

    忙しいので、日本語を勉強をしなくなりました。[I am busy so I stopped studying Japanese]

  6. 亡くなる – to die (verb, intrans.)
    ディックは10歳のときなくなりました。 [Dick died at ten years of age.]