(a.) Morally or legally binding; mandatory; imperative; as, obedience is obligatory on a soldier; imposing duty or obligation; requiring performance or forbearance of some act; -- often followed by on or upon.
Thesaurus Entries
absolute, binding, choiceless, compulsory, conclusive, de rigueur, decisive, decretory, demanded, dictated, entailed, essential, exigent, final, hard-and-fast, imperative, imperious, importunate, imposed, incumbent, indispensable, inevitable, involuntary, irrevocable, mandated, mandatory, must, necessary, necessitous, peremptory, prescript, prescriptive, required, requisite, ultimate, urgent, without appeal, without choice
