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]

Moby Thesaurus II by Grady Ward, 1.0:

298 Moby Thesaurus words for "prompt":
   accordant, acquiescent, admonish, adumbrate, affect, affirmative,
   agile, agog, agreeable, agreeing, aide-memoire, alacritous, alert,
   alive, all agog, allude to, amenable, animated, anxious, approving,
   apt, ardent, argue into, arouse, assenting, attentive, avid, awake,
   awaken, bend, bias, breakneck, breathless, bright, bring,
   bring about, bring around, bring to recollection, brisk,
   broad hint, bursting to, cajole, call forth, call up, carry,
   carry back, cause, caution, charge, clue, coax, color, compliable,
   compliant, consentient, consenting, content, convince, cooperative,
   cue, cursory, dashing, decide, decisive, desirous, determine,
   dispatchful, dispose, disposed, docile, double-quick, draw,
   drop a hint, eager, eagle-winged, egg on, elicit, encourage,
   endorsing, engage, enjoin, enlist, enthusiastic, evoke, exhort,
   expeditious, expostulate, express, fain, fast, favorable,
   favorably disposed, favorably inclined, festinate, feverish,
   flapper, fleet, flying, forward, full of life, furious, galloping,
   game, gentle hint, gesture, get, get to do, give a hint,
   give rise to, give the cue, glance at, glimmer, glimmering, goad,
   hair-trigger, hasty, headlong, help, hint, hint at,
   hold the promptbook, hurried, hustling, immediate, impatient,
   impel, implication, imply, in the mind, in the mood, incite,
   incline, inclined, index, indicate, indication, induce, influence,
   inkling, innuendo, insinuate, insinuation, inspire, instant,
   instantaneous, interest in, intimate, intimation, issue a caveat,
   jog the memory, jogger, keen, kick, last-minute, lead,
   light of heel, light-footed, lively, look, lure, memorandum,
   mercurial, minded, motivate, move, muster up, nag, nimble,
   nimble-footed, nod, nothing loath, nudge, occasion, on the,
   on the alert, on the ball, on the job, on the spot, on time,
   panting, passing, permissive, persuade, pliant, preach,
   precipitate, predispose, predisposed, prevail, prevail on,
   prevail upon, prick, procure, prod, prompt the mind, prompter,
   prompting, prone, propel, provoke, punctual, put in mind,
   put in remembrance, qui vive, quick, quick as lightning,
   quick as thought, rapid, raring to, ratifying, ready,
   ready and willing, recall, receptive, reckless, remember,
   remembrance, remembrancer, remind, remind one of, reminder,
   remonstrate, responsive, rouse, running, sanctioning, scent, sharp,
   sic, sign, signal, slap-bang, slapdash, sleepless, smart, snap,
   snappy, soften up, spanking, speedy, spirited, spoor, spry, spur,
   stimulate, stimulus, submissive, suggest, suggestion, summary,
   summon up, superficial, suspicion, sway, swift, symptom, talk into,
   telltale, tempt, tickler, timely, tinge, tone, track, tractable,
   unblinking, ungrudging, unhesitating, unloath, unnodding,
   unrefusing, unreluctant, unsleeping, unwinking, urge, urgent,
   vigilant, vital, vivacious, vivid, wakeful, warn, watchful,
   wear down, weigh with, well-disposed, well-inclined, whisper,
   wide-awake, willed, willing, willinghearted, win over, winged,
   wink, work, zealous, zestful