The Collaborative International Dictionary of English v.0.48:

Whit \Whit\, n. [OE. wight, wiht, AS. wiht a creature, a thing.
   See Wight, and cf. Aught, Naught.]
   The smallest part or particle imaginable; a bit; a jot; an
   iota; -- generally used in an adverbial phrase in a negative
   sentence. "Samuel told him every whit." --1 Sam. iii. 18.
   "Every whit as great." --South.
   [1913 Webster]

         So shall I no whit be behind in duty.    --Shak.
   [1913 Webster]

         It does not me a whit displease.         --Cowley.
   [1913 Webster]

WordNet (r) 3.0 (2006):

whit
    n 1: a tiny or scarcely detectable amount [syn: shred,
         scintilla, whit, iota, tittle, smidgen,
         smidgeon, smidgin, smidge]

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "whit":
   ace, atom, bit, dab, damn, dole, dot, dram, dribble, driblet,
   dwarf, farthing, fleck, flyspeck, fragment, gobbet, grain, granule,
   groat, hair, handful, hoot, iota, jot, little, little bit, lota,
   minim, minimum, minutiae, mite, modicum, molecule, mote, nutshell,
   ounce, particle, pebble, pinch, pittance, point, scruple, shred,
   smidgen, smitch, speck, spoonful, spot, thimbleful, tiny bit,
   tittle, trifling amount, trivia, whoop