na-adjective, noun
irresponsible; carefree; sloppy
Describes a person or attitude that is easygoing to the point of being unreliable, heedless, or slipshod. Often carries a negative or critical tone.
彼のちゃらんぽらんな態度には本当に困っている。
I'm really troubled by his irresponsible attitude.
あの人はいつもちゃらんぽらんで、約束を守ったことがない。
That person is always so careless and has never kept a promise.