1. I-adjective (keiyoushi)

   wasteful; a waste

   Usually written using kana alone

   とてもいい天気だから家の中にいるのがもったいない。

2. too good; more than one deserves; unworthy of

   Usually written using kana alone

3. impious; profane; sacrilegious

   Usually written using kana alone

Also written 勿体無い【もったいない】mottainai