"a scheme already carried into execution," 19c., French, literally "an accomplished fact." See feat and accomplish.
Entries linking to fait accompli
feat n.
mid-14c., "action, deeds," from Anglo-French fet, from Old French fait "action, deed, achievement" (12c.), from Latin factum "thing done," a noun based on the past participle of facere "to make, to do," from PIE root *dhe- "to set, put." Sense of "exceptional or noble deed" arose c. 1400 from phrase feat of arms (French fait d'armes).
accomplish v.
late 14c., "fulfill, perform, carry out an undertaking," from Old French acompliss-, present-participle stem of acomplir "to fulfill, fill up, complete" (12c., Modern French accomplir), from Vulgar Latin *accomplere, from Latin ad "to" (see ad-) + complere "to fill up," transferred to "fulfill, finish (a task)," from com-, here probably as an intensive prefix (see com-), + plere "to fill" (from PIE root *pele- (1) "to fill"). Related: Accomplished; accomplishing.