na-adjective
unconcerned; unbothered; nonchalant
Describes a casual, carefree attitude toward something that might normally worry or bother others. Often used in the pattern 〜なんてへっちゃらだ or 〜はへっちゃらだ.
彼は失敗してもへっちゃらな顔をしている。
He looks completely unconcerned even when he fails.
このくらいの寒さはへっちゃらだ。
This much cold doesn't bother me at all.
na-adjective
Used to say that something is so easy it's no trouble at all. Often appears in phrases like 〜なんてへっちゃらだ or 〜はへっちゃらだ.
この問題はへっちゃらだよ。
This problem is a piece of cake.
彼は難しい仕事もへっちゃらでこなす。
He handles even difficult tasks with ease.
The origin is uncertain. It may be a sound-symbolic word (mimetic) expressing a light, carefree feeling, but the exact derivation is unclear.