The Collaborative International Dictionary of English v.0.48:

Grizzle \Griz"zle\, n. [F. gris: cf. grisaille hair partly gray,
   fr. gris gray. See Gris, and cf. Grisaille.]
   Gray; a gray color; a mixture of white and black. --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Grizzle \Griz"zle\, v. t. & i.
   To make or become grizzly, or grayish.
   [Webster 1913 Suppl.]

         Hardship of the way such as would grizzle little
         children.                                --R. F.
                                                  Burton.
   [Webster 1913 Suppl.]

         I found myself on the Nubian desert shaking hands with
         a
         grizzling man whom men addressed as Collins Bey. --Pall
                                                  Mall Mag.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Grizzle \Griz"zle\, v. i. & t. [Etym. uncertain.]
   To worry; to fret; to bother; grumble. [Prov. Eng.] "Don't
   sit grizzling there." --Charles Reade.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

grizzle
    n 1: a grey wig
    v 1: be in a huff; be silent or sullen [syn: grizzle, brood,
         stew]
    2: complain whiningly [syn: whine, grizzle, yammer,
       yawp]

Moby Thesaurus II by Grady Ward, 1.0:

80 Moby Thesaurus words for "grizzle":
   Quaker-colored, acier, ashen, ashy, bay, bayard, besnow, blanch,
   bleach, buckskin, calico pony, canescent, chalk, chestnut,
   cinereous, cinerous, dapple, dapple-gray, dappled, dappled-gray,
   dingy, dismal, dove-colored, dove-gray, dreary, dull, dun, dusty,
   etiolate, frost, glaucescent, glaucous, gray, gray-black,
   gray-brown, gray-colored, gray-drab, gray-green, gray-spotted,
   gray-toned, gray-white, grayed, grayish, griseous, grizzled,
   grizzly, iron-gray, lead-gray, leaden, livid, mouse-colored,
   mouse-gray, mousy, paint, painted pony, pearl, pearl-gray, pearly,
   piebald, pinto, roan, sad, silver, silver-gray, silvered, silvery,
   skewbald, slate-colored, slaty, smoke-gray, smoky, sober, somber,
   sorrel, steel-gray, steely, stone-colored, taupe, white, whiten