a highly successful, unexpected stroke, act, or move; a clever action or accomplishment.

(among the Plains Indians of North America) a brave or reckless deed performed in battle by a single warrior, as touching or striking an enemy warrior without sustaining injury oneself.

coup d'état. ?

count coup

(among Plains Indians of North America)

to perform a coup.

to recount or relate the coups one has performed.

noun

accomplishment , action , coup de mitre , coup d’tat , deed , exploit , feat , overthrow , plot , revolution , stratagem , stroke , stroke of genius , stunt , successful stroke , tour de force , upset , achievement , attack , mastery , overturn , plan , strike , takeover