Meaning

• (grammar) 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.

  "The verbs in sentences like "Do it!" and "Say what you like!" are in the imperative."

• (grammar) A verb in imperative mood.

• An essential action, a must: something which is imperative.

  "Visiting Berlin is an imperative."

Meaning

• Essential; crucial; extremely important.

  "It is imperative that you come here right now."

• (grammar) Of, or relating to the imperative mood.

• Having semantics that incorporates mutable variables.

• Expressing a command; authoritatively or absolutely directive.

  "imperative orders"