Definition of: imperative

(im·per′ə·tiv) adjective
1. Expressive of or containing positive, as distinguished from advisory or discretionary, command; authoritative; peremptory.
2. Gram. Designating that mood of the verb which expresses command, entreaty, or exhortation.
3. Not to be evaded or avoided; obligatory.
—noun
1. That which is imperative.
2. Gram. The mood of the verb which expresses command; also, a verb in this mood. [<L imperativus <imperare command]
—im·per′a·tive·ly adverb
—im·per′a·tive·ness noun