Source : Webster's Revised Unabridged Dictionary (1913)

Cautionary \Cau"tion*a*ry\, a.
   1. Conveying a caution, or warning to avoid danger; as,
      cautionary signals.

   2. Given as a pledge or as security.

            He hated Barnevelt, for his getting the cautionary
            towns out of his hands.               --Bp. Burnet.

   3. Wary; cautious. [Obs.] --Bacon.

Source : WordNet®

cautionary
     adj 1: tending to ward off; "the swastika...a very ancient
            prophylactic symbol occurring among all peoples"-
            Victor Schultze [syn: {preventive}, {prophylactic}]
     2: serving to warn; "shook a monitory finger at him"; "an
        exemplary jail sentence" [syn: {admonitory}, {exemplary},
        {monitory}, {warning(a)}]