Source : Webster's Revised Unabridged Dictionary (1913)

Hat \Hat\, a.
   Hot. [Obs.] --Chaucer.

Hat \Hat\,
   sing. pres. of {Hote} to be called. Cf. {Hatte}. [Obs.]
   ``That one hat abstinence.'' --Piers Plowman.

Hat \Hat\, n. [AS. h[ae]t, h[ae]tt; akin to Dan. hat, Sw. hatt,
   Icel. hattr a hat, h["o]ttr hood, D. hoed hat, G. hut, OHG.
   huot, and prob. to L. cassis helmet. ???. Cf.{Hood}.]
   A covering for the head; esp., one with a crown and brim,
   made of various materials, and worn by men or women for
   protecting the head from the sun or weather, or for ornament.

   {Hat block}, a block on which hats are formed or dressed.

   {To pass around the hat}, to take up a collection of
      voluntary contributions, which are often received in a
      hat. [Collog.] --Lowell.

Source : WordNet®

hat
     v 1: put on or wear a hat; "He was unsuitably hatted"
     2: furnish with a hat
     [also: {hatting}, {hatted}]

hat
     n 1: headdress that protects the head from bad weather; has
          shaped crown and usually a brim [syn: {chapeau}, {lid}]
     2: an informal term for a person's role; "he took off his
        politician's hat and talked frankly"
     [also: {hatting}, {hatted}]

Source : Free On-Line Dictionary of Computing

hat
     
        A common (spoken) name for the circumflex ("^", ASCII 94)
        character.
     
        See {ASCII} for other synonyms.
     
        [{Jargon File}]