obligatory Synonyms

mandatory essential indispensable compulsory inescapable required needful imperative necessary binding bounden unavoidable pressing prescribed prerequisite peremptory payable obligation needed requisite restringing conforming to accepted standards incumbent on de rigueur nonelective mandatorily of the essence all important vital urgent unavoided sumptuary substantive stipulated statutory must ministerial astrictive enforced dictated demanded crucial critical constraining compulsatory compelling coercive clamant bindingly exigent