expression
not feel satisfied; can't feel at ease
Expresses a lingering feeling of dissatisfaction or unease, often because something feels unresolved or incomplete. Commonly used in negative form.
謝ってもらわないと気が済まない。
I won't feel satisfied unless I get an apology.
彼は最後まで言いたいことを言わないと気が済まない性格だ。
He's the type who can't feel at ease unless he says everything he wants to say.
The affirmative form meaning 'to feel satisfied' or 'to feel at ease'; 気が済まない is its negative counterpart.
From 気 (mind, feeling) + 済む (to finish, to be settled) in negative form. Literally 'one's mind does not settle'.