imperative

(noun) a mood that expresses an intention to influence the listener's behavior. Synonyms: imperative mood, jussive mood, imperative form.

(noun) some duty that is essential and urgent.

(adj) requiring attention or action. Synonyms: imperative (vs. beseeching). Examples: "As nuclear weapons proliferate, preventing war becomes imperative." "Requests that grew more and more imperative."

(adj) relating to verbs in the imperative mood.