What does もったいない mean?
もったいない is a Japanese noun meaning “wasteful; more than one deserves, unworthy of” in English. It can also be translated as “too good, impious” depending on context. It is written as もったいない in hiragana, and mottainai in romaji. This word is part of JLPT N3 vocabulary.
Example sentence
とてもいい天気だから家の中にいるのがもったいない。
It's too sunny to stay inside.