1520s, "overthrown, routed" (now obsolete in this sense), from Latin profligatus "destroyed, ruined, corrupt, abandoned, dissolute," past participle of profligare "to cast down, defeat, ruin," from pro "down, forth" (see pro-) + fligere "to strike" (see afflict). Main modern meaning "recklessly extravagant" is 1779, via notion of "ruined by vice" (1640s, implied in a use of profligation). Related: Profligately. As a noun from 1709.
