expression, i-adjective
insincere; not what one really feels
Used to describe words or actions that do not reflect one's true feelings, often in set phrases like 心にもないことを言う (say something one doesn't mean).
彼は心にもないお世辞を言った。
He paid a compliment he didn't really mean.
心にもないことを言ってしまって後悔している。
I regret saying something I didn't mean.
本心 is a noun meaning 'true feelings' or 'real intention', while 心にもない is an adjective-like expression describing words or actions that are not from the heart.
建前 refers to a publicly stated position or principle that may differ from one's true feelings (本音), whereas 心にもない focuses on the insincerity of a specific utterance or action.
Phrase composed of 心 (heart, mind) + に (particle) + も (even) + ない (not exist). Literally 'not even in one's heart', meaning something is not truly felt.