Something that is compulsory or required.
Having the power of compulsion; constraining.
Required; obligatory; mandatory.
An essential action, a must: something which is imperative.
A verb in imperative mood.
The grammatical mood expressing an order (see jussive). In English, the imperative form of a verb is the same as that of the bare infinitive.
Having semantics that incorporates mutable variables.
Expressing a command; authoritatively or absolutely directive.
Essential; crucial; extremely important.
Of, or relating to the imperative mood.