Source : Webster's Revised Unabridged Dictionary (1913)

   {Jack crosstree}. (Naut.) See 10, b, above.

   {Jack curlew} (Zo["o]l.), the whimbrel.

   {Jack frame}. (Cotton Spinning) See 4
       (g), above.

   {Jack Frost}, frost personified as a mischievous person.

   {Jack hare}, a male hare. --Cowper.

   {Jack lamp}, a lamp for still hunting and camp use. See def.
      4
       (n.), above.

   {Jack plane}, a joiner's plane used for coarse work.

   {Jack post}, one of the posts which support the crank shaft
      of a deep-well-boring apparatus.

   {Jack pot} (Poker Playing), the name given to the stakes,
      contributions to which are made by each player
      successively, till such a hand is turned as shall take the
      ``pot,'' which is the sum total of all the bets.

Frost \Frost\, n. [OE. frost, forst, AS. forst, frost. fr.
   fre['o]san to freeze; akin to D. varst, G., OHG., Icel.,
   Dan., & Sw. frost. [root]18. See {Freeze}, v. i.]
   1. The act of freezing; -- applied chiefly to the congelation
      of water; congelation of fluids.

   2. The state or temperature of the air which occasions
      congelation, or the freezing of water; severe cold or
      freezing weather.

            The third bay comes a frost, a killing frost.
                                                  --Shak.

   3. Frozen dew; -- called also {hoarfrost} or {white frost}.

            He scattereth the frost like ashes.   --Ps. cxlvii.
                                                  16.

   4. Coldness or insensibility; severity or rigidity of
      character. [R.]

            It was of those moments of intense feeling when the
            frost of the Scottish people melts like a snow
            wreath.                               --Sir W.
                                                  Scott.

   {Black frost}, cold so intense as to freeze vegetation and
      cause it to turn black, without the formation of
      hoarfrost.

   {Frost bearer} (Physics), a philosophical instrument
      illustrating the freezing of water in a vacuum; a
      cryophous.

   {Frost grape} (Bot.), an American grape, with very small,
      acid berries.

   {Frost lamp}, a lamp placed below the oil tube of an Argand
      lamp to keep the oil limpid on cold nights; -- used
      especially in lighthouses. --Knight.

   {Frost nail}, a nail with a sharp head driven into a horse's
      shoe to keen him from slipping.

   {Frost smoke}, an appearance resembling smoke, caused by
      congelation of vapor in the atmosphere in time of severe
      cold.

            The brig and the ice round her are covered by a
            strange black obscurity: it is the frost smoke of
            arctic winters.                       --Kane.

   {Frost valve}, a valve to drain the portion of a pipe,
      hydrant, pump, etc., where water would be liable to
      freeze.

   {Jack Frost}, a popular personification of frost.

Source : WordNet®

Jack Frost
     n : a personification of frost or winter weather