[n] some duty that is essential and urgent
[n] a mood that expresses an intention to influence the listener's behavior
[adj] requiring attention or action; "as nuclear weapons proliferate, preventing war becomes imperative"; "requests that grew more and more imperative"
[adj] (grammar) relating to verbs in the imperative mood
adjuratory, clamant, commanding, crying, desperate, exigent, imperative mood, insistent, instant, jussive mood, peremptory, pressing, urgent