1690s, originally of medicines, "forceful, vigorous," especially in effect on bowels, from Greek drastikos "effective, efficacious; active, violent," from drasteon "(thing) to be done," from drāo "to do, make, act, perform" (especially some great deed, whether good or bad), which is of uncertain etymology. Sense of "extreme, severe, acting with force or violence" is recorded by 1808. Related: Drastically.
