compulsory (adj.)

1580s, "obligatory, arising from compulsion, done under compulsion," from Medieval Latin compulsorius, from Latin compulsus, past participle of compellere "to drive together, force," from com "with, together" (see com-) + pellere "to drive" (from PIE root *pel- (5) "to thrust, strike, drive"). As "coercive, exercising compulsion" from 1630s. As a noun from 1510s, originally "a compulsory means." Related: Compulsories; compulsorily; compulsoriness.