Source : Webster's Revised Unabridged Dictionary (1913)

Whim \Whim\, n. [Cf. Icel. hwima to wander with the eyes, vim
   giddiness, Norw. kvima to whisk or flutter about, to trifle,
   Dan. vimse to skip, whisk, jump from one thing to another,
   dial. Sw. hvimsa to be unsteady, dizzy, W. chwimio to move
   briskly.]
   1. A sudden turn or start of the mind; a temporary
      eccentricity; a freak; a fancy; a capricious notion; a
      humor; a caprice.

            Let every man enjoy his whim.         --Churchill.

   2. (Mining) A large capstan or vertical drum turned by horse
      power or steam power, for raising ore or water, etc., from
      mines, or for other purposes; -- called also {whim gin},
      and {whimsey}.

   {Whim gin} (Mining), a whim. See {Whim}, 2.

   {Whim shaft} (Mining), a shaft through which ore, water,
      etc., is raised from a mine by means of a whim.

   Syn: Freak; caprice; whimsey; fancy.

   Usage: {Whim}, {Freak}, {Caprice}. Freak denotes an
          impulsive, inconsiderate change of mind, as by a child
          or a lunatic. Whim is a mental eccentricity due to
          peculiar processes or habits of thought. Caprice is
          closely allied in meaning to freak, but implies more
          definitely a quality of willfulness or wantonness.

Whim \Whim\, v. i.
   To be subject to, or indulge in, whims; to be whimsical,
   giddy, or freakish. [R.] --Congreve.

Whim \Whim\, n. [Cf. {Whimbrel}.] (Zo["o]l.)
   The European widgeon. [Prov. Eng.]

Source : WordNet®

whim
     n 1: a sudden desire; "he bought it on an impulse" [syn: {caprice},
           {impulse}]
     2: an odd or fanciful or capricious idea; "the theatrical
        notion of disguise is associated with disaster in his
        stories"; "he had a whimsy about flying to the moon";
        "whimsy can be humorous to someone with time to enjoy it"
        [syn: {notion}, {whimsy}, {whimsey}]