imperative

adj

1. Essential; crucial; extremely important.

   “That you come here right now is imperative.”

   “Meantime, alterations at King William Street had become imperative, and by December 22, 1895, the station had been remodelled, as at Stockwell, to provide an island platform with lines each side, and a scissors crossing.”

   “Give this document to Ozzy. It's imperative that he reads and understands it. Got it?”

2. Of, or relating to the imperative mood.
3. Having semantics that incorporates mutable variables.
4. Expressing a command; authoritatively or absolutely directive.

   “imperative orders”

   “The suits of kings are imperative.”

noun

1. (uncountable)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.”

2. (countable)A verb in the imperative mood.
3. (countable)An essential action, a must: something which is imperative.

   “Visiting Berlin is an imperative.”

   “Anything grandiose or historically based tends to sound flat and banal when it reaches English, partly because translators get stuck between contradictory imperatives: juggling fidelity to the original sense with what is vocally viable, they tend to resort to a genteel fustian which lacks either poetic resonance or demotic realism, adding to a sense of artificiality rather than enhancing credibility.”

   “The new imperative for investment is the Government's objective to secure carbon-neutral transport emissions by 2040.”