—adj.
1 urgent.
2 obligatory.
3 commanding, peremptory.
4 Gram. (of a mood) expressing a command (e.g. come here!).
—n.
1 Gram. the imperative mood.
2 a command.
Derivatives:
imperatival adj. imperatively adv. imperativeness n.
Etymology: LL imperativus f. imperare command (as IN-(2), parare make ready)
Useful english dictionary. 2012.