mid-14c., "to drive by physical force; to try, attempt, strive; to fortify, strengthen a place;" late 14c. as "exert force, compel; make stronger, reinforce; strengthen an argument; grow stronger, become violent," from Old French enforcier "strengthen, reinforce; use force (on), offer violence (to); oppress; violate, rape" (12c.) or a native formation from en-(1) "make, put in" + force, n.. Meaning "compel obedience to (a law, etc.) is from 1640s. Related: Enforced; enforcing.