Definition of compulsory:
domineering, supreme, controlling, compulsive, peremptory, arbitrary, irresponsible, despotic, incumbent, needful, without fail, tyrannical, basic, dogmatic, imperious, exacting, of necessity, dictatorial, obligation, at all costs, positive, willing, commanding, coercive, autocratic, unconditional, overbearing, authoritative, forced, haughty, absolute, unequivocal, lordly, nonelective, needed, vital, arrogant.
- obligatory (part of speech: adjective)
- required (part of speech: adjective)
- "Wage Earning and Education", R. R. Lutz.
- "Hinduism and Buddhism, Vol I. (of 3) An Historical Sketch", Charles Eliot.
- "Hypatia or, New Foes with an Old Face", Charles Kingsley.