The Collaborative International Dictionary of English v.0.48:

Prompt \Prompt\ (pr[o^]mt; 215), a. [Compar. Prompter; superl.
   Promptest.] [F. prompt, L. promptus, properly, brought
   forth (to light or view), hence, visible, evident, at hand,
   ready, quick, -- p. p. of promere to take or bring forth; pro
   forth + emere to take. See Redeem. ]
   [1913 Webster]
   1. Ready and quick to act as occasion demands; meeting
      requirements readily; not slow, dilatory, or hesitating in
      decision or action; responding on the instant; immediate;
      as, prompt in obedience or compliance; -- said of persons.
      [1913 Webster]

            Very discerning and prompt in giving orders.
                                                  --Clarendon.
      [1913 Webster]

            Tell him I am prompt
            To lay my crown at's feet.            --Shak.
      [1913 Webster]

            And you, perhaps, too prompt in your replies.
                                                  --Dryden.
      [1913 Webster]

   2. Done or rendered quickly, readily, or immediately; given
      without delay or hesitation; -- said of conduct; as,
      prompt assistance.
      [1913 Webster]

            When Washington heard the voice of his country in
            distress,
            his obedience was prompt.             --Ames.
      [1913 Webster]

   3. Easy; unobstructed. [Obs.]
      [1913 Webster]

            The reception of the light into the body of the
            building was very prompt.             --Sir H.
                                                  Wotton.
      [1913 Webster]

   Syn: Ready; expeditious; quick; agile; alert; brisk; nimble.

   Usage: Prompt, Ready, Expeditious. One who is ready is
          prepared to act at the moment. One who is prompt acts
          at the moment. One who is expeditious carries through
          an undertaking with constant promptness.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Prompt \Prompt\, n. (Com.)
   A limit of time given for payment of an account for produce
   purchased, this limit varying with different goods. See
   Prompt-note.
   [1913 Webster]

         To cover any probable difference of price which might
         arise before the expiration of the prompt, which for
         this article [tea] is three months.      --J. S. Mill.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Prompt \Prompt\, v. t. [imp. & p. p. Prompted; p. pr. & vb. n.
   Prompting.]
   [1913 Webster]
   1. To assist or induce the action of; to move to action; to
      instigate; to incite.
      [1913 Webster]

            God first . . . prompted on the infirmities of the
            infant world by temporal prosperity.  --Jer. Taylor.
      [1913 Webster]

   2. To suggest; to dictate.
      [1913 Webster]

            And whispering angles prompt her golden dreams.
                                                  --Pope.
      [1913 Webster]

   3. To remind, as an actor or an orator, of words or topics
      forgotten.
      [1913 Webster]

WordNet (r) 3.0 (2006):

prompt
    adj 1: according to schedule or without delay; on time; "the
           train is prompt"
    2: ready and willing or quick to act; "she is always prompt to
       help her friends";
    3: performed with little or no delay; "an immediate reply to my
       letter"; "a prompt reply"; "was quick to respond"; "a
       straightaway denial" [syn: immediate, prompt, quick,
       straightaway]
    n 1: a cue given to a performer (usually the beginning of the
         next line to be spoken); "the audience could hear his
         prompting" [syn: prompt, prompting]
    2: (computer science) a symbol that appears on the computer
       screen to indicate that the computer is ready to receive a
       command [syn: prompt, command prompt]
    v 1: give an incentive for action; "This moved me to sacrifice
         my career" [syn: motivate, actuate, propel, move,
         prompt, incite]
    2: serve as the inciting cause of; "She prompted me to call my
       relatives" [syn: prompt, inspire, instigate]
    3: assist (somebody acting or reciting) by suggesting the next
       words of something forgotten or imperfectly learned [syn:
       prompt, remind, cue]