requisite Synonyms

necessary essential needed needful indispensable required requirement mandatory must-have demanded necessity condition compulsory appropriate prerequisite prop stipulation precondition relevant relevance pressing proviso provision property proper sufficient systemic prerequisite condition called-for sine qua non essentials life-or-death life-and-death apropos axiological of the essence all important want vital urgent unavoidable paramount fit enough enforced due determinative desideratum deserved demand