The Collaborative International Dictionary of English v.0.48:

Caution \Cau"tion\, n. [F. caution a security, L. cautio, fr.
   cavere (For scavere) to be on one's guard, to take care
   (orig.) to be on the watch, see; akin to E. show.]
   1. A careful attention to the probable effects of an act, in
      order that failure or harm may be avoided; prudence in
      regard to danger; provident care; wariness.
      [1913 Webster]

   2. Security; guaranty; bail. [R.]
      [1913 Webster]

            The Parliament would yet give his majesty sufficient
            caution that the war should be prosecuted.
                                                  --Clarendon.
      [1913 Webster]

   3. Precept or warning against evil of any kind; exhortation
      to wariness; advice; injunction.
      [1913 Webster]

            In way of caution I must tell you.    --Shak.
      [1913 Webster]

   4. (Civil & Scots Law) A pledge, bond, or other security for
      the performance of an obligation either in or out of
      judicial proceedings; the promise or contract of one not
      for himself but another; security.
      [Webster 1913 Suppl.]

   Caution money, money deposited by way of security or
      guaranty, as by a student at an English university.

   Syn: Care; forethought; forecast; heed; prudence;
        watchfulness; vigilance; circumspection; anxiety;
        providence; counsel; advice; warning; admonition.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Caution \Cau"tion\ v. t. [imp. & p. p. Cautioned; p. pr. & vb.
   n. Cautioning.]
   To give notice of danger to; to warn; to exhort [one] to take
   heed.
   [1913 Webster]

         You cautioned me against their charms.   --Swift.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

163 Moby Thesaurus words for "caution":
   TLC, admonish, admonishment, admonition, advice, advise, advising,
   advocacy, alarm, alert, alerting, alertness, anticipation,
   attention, briefing, canniness, care, carefulness, caution money,
   cautioning, cautiousness, caveat, charge, circumspection,
   circumspectness, clue, collateral, collateral security, concern,
   consideration, consultation, council, counsel, cry havoc,
   cry out against, cue, daunt, deposit, determent, deterrence,
   deterrent example, diffidence, direction, discreetness, discretion,
   disinclination to believe, dissuade, encourage, enjoin, example,
   exhort, exhortation, expostulate, expostulation, falter, faltering,
   final notice, final warning, foresight, forethought, forewarn,
   forewarning, forfeit, frighten off, frightening off,
   give fair warning, give notice, give warning, guardedness,
   guidance, heed, heedfulness, hesitance, hesitancy, hesitating,
   hesitation, hint, hortation, idea, incite, inconvincibility,
   incredulity, induce, injunction, instruction, intimidate,
   intimidation, issue a caveat, issue an ultimatum, kid out of,
   leeriness, lesson, loving care, margin, mindfulness, monition,
   moral, move, notice, notification, notify, object lesson, office,
   opinion, parley, passing word, persuade, pointer, preach,
   precaution, preconsideration, predeliberation, premeditation,
   preparedness, prompt, proposal, providence, prudence,
   recommendation, regard, regardfulness, remonstrance, remonstrate,
   resistiveness to belief, shilly-shally, shilly-shallying,
   skepticism, solicitude, sound the alarm, stake, steer, suggestion,
   suspicion, suspiciousness, talk out of, talking out of,
   tender loving care, tentativeness, thought, thoughtfulness, threat,
   threaten, tip, tip off, tip-off, tough-mindedness, ultimatum,
   unconvincibility, uncredulousness, unpersuadability, unpersuade,
   unpersuasibility, urge, utter a caveat, verbum sapienti, vigilance,
   wariness, warn, warn against, warning, warning piece, watchfulness,
   whisper