noun
distinction between right and wrong
Almost exclusively used in the negative phrase 頑是ない (or 頑是がない), meaning 'innocent' or 'unable to tell right from wrong', especially of young children. The standalone noun is rare.
まだ頑是ない子供だから、悪気はなかったんだ。
He's still a child who can't tell right from wrong, so he didn't mean any harm.