The Collaborative International Dictionary of English v.0.48:

Imperative \Im*per"a*tive\, n. (Gram.)
   The imperative mood; also, a verb in the imperative mood.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Imperative \Im*per"a*tive\, a. [L. imperativus, fr. imperare to
   command; pref. im- in + parare to make ready, prepare: cf. F.
   imp['e]ratif. See Perade, and cf. Empire.]
   1. Expressive of command; containing positive command;
      authoritatively or absolutely directive; commanding;
      authoritative; as, imperative orders.
      [1913 Webster]

            The suit of kings are imperative.     --Bp. Hall.
      [1913 Webster]

   2. Not to be avoided or evaded; obligatory; binding;
      compulsory; as, an imperative duty or order.
      [1913 Webster]

   3. (Gram.) Expressive of command, entreaty, advice, or
      exhortation; as, the imperative mood.
      [1913 Webster]

WordNet (r) 3.0 (2006):

imperative
    adj 1: requiring attention or action; "as nuclear weapons
           proliferate, preventing war becomes imperative";
           "requests that grew more and more imperative" [ant:
           beseeching, imploring, pleading]
    2: relating to verbs in the imperative mood
    n 1: a mood that expresses an intention to influence the
         listener's behavior [syn: imperative mood, imperative,
         jussive mood, imperative form]
    2: some duty that is essential and urgent

The Free On-line Dictionary of Computing (19 January 2023):

imperative language
imperative
imperative programming

    Any programming language that specifies explicit
   manipulation of the state of the computer system, not to be
   confused with a procedural language, which specifies an
   explicit sequence of steps to perform.

   An example of an imperative (but non-procedural) language is a
   data manipulation language for a relational database
   management system.  This specifies changes to the database
   but does not necessarily require anyone to specify a sequence
   of steps.

   Both contrast with declarative languages, which specify
   neither explicit state manipulation nor a sequence of steps.

   (2007-10-02)