imperative
/ˌɪmˈpɛɹətɪv/
absolutely necessary or required; vital
imperative in a sentence
“It is imperative that we meet this deadline.”
Origin of imperative
Latin imperativus specially ordered (from imperare to command)
Related Words
mandatory
required by law or rules; compulsory
discretionary
available for use at one's own judgment
optional
available to be chosen but not required
ancillary
providing necessary support; supplementary
predicate
to base something on; require as a precondition
entail
to involve something as a necessary consequence