にたにた

adverb, adverb taking the 'to' particle, noun or participle which takes 'suru'

grinning broadly; smirking

Describes a wide, often unpleasant or self-satisfied grin. Typically used with 笑う or する, and often carries a negative or mocking nuance.

• 彼かれはいたずらが成せい功こうして、にたにた笑わらった。

  He grinned broadly when his prank succeeded.

• あの男おとこはいつもにたにたしていて、感かんじが悪わるい。

  That guy is always smirking and gives off a bad vibe.