Refers to a subtle outward sign or hint of someone's inner feelings, intentions, or state of mind. Often used in negative or questioning contexts to say that no such sign is visible.
There wasn't the slightest sign of anger on his face.
She didn't show even a hint that she wanted to break up.
Compound of 気 (ki, 'mind, spirit') and 振り (furi, 'manner, appearance'), with rendaku voicing to ぶり. The exact historical derivation is uncertain, but the word has been used since at least the Edo period.