esprit de l'escalier

[ es-pree duh le-skahl-yey ]
/ ɛsˈpri də lɛˈskɑl yeɪ /

noun French.

a perfect comeback or witty remark that one frustratingly comes up with only when the moment for doing so has passed: Writers, by nature, tend to be people in whom l' esprit de l'escalier is a recurrent experience.

Origin of esprit de l'escalier

First recorded in 1905–10; literally, “wit of the staircase” (i.e., after one has left the gathering)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019