ETYM French, fromL. colaphus a cuff, Greek.
(French) “stroke”; successful action; coup d’état. coup de grâce, finishing blow; fatal blow. coup de main, sudden violent onslaught. coup d’essai, experiment. coup d’état, sudden action whereby government is changed; short revolution, especially bloodless. coup d’oeil, swift survey or glance; what is thus seen. coup de soleil, sunstroke. coup de théâtre, sudden dramatic or sensational action.(Homonym: coo).
A brilliant and notable success. co-up.

Chiefly Scottish; overturn, upset