A person who finesses; someone who handles situations with skill, diplomacy, and subtle strategy.
From 'finesse' plus '-er' (agent noun suffix). The '-er' suffix creates nouns meaning 'one who does X,' so a finesser is one who finesses.
The '-er' suffix is so productive in English that you can turn almost any verb into a person—'run' becomes 'runner,' so 'finesse' becomes 'finesser,' which is why new job titles feel natural even if they're brand new.
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