The Collaborative International Dictionary of English v.0.48:

Hat \Hat\ (h[a^]t), 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. [root]13. 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.
   [1913 Webster]

   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. [Colloq.] --Lowell.
      [1913 Webster]