The Collaborative International Dictionary of English v.0.48:

Variegate \Va"ri*e*gate\, v. t. [imp. & p. p. Variegated; p.
   pr. & vb. n. Variegating.] [L. variegatus, p. p. of
   variegare to variegate; varius various + agere to move, make.
   See Various, and Agent.]
   To diversify in external appearance; to mark with different
   colors; to dapple; to streak; as, to variegate a floor with
   marble of different colors.
   [1913 Webster]

         The shells are filled with a white spar, which
         variegates and adds to the beauty of the stone.
                                                  --Woodward.
   [1913 Webster]

WordNet (r) 3.0 (2006):

variegate
    v 1: change the appearance of, especially by marking with
         different colors
    2: make something more diverse and varied; "Vary the menu" [syn:
       vary, variegate, motley]

Moby Thesaurus II by Grady Ward, 1.0:

50 Moby Thesaurus words for "variegate":
   band, bar, bespangle, bespeckle, bespot, blotch, break up, check,
   checker, dapple, differ, differentiate, dissent, disunify,
   divaricate, diverge, diversify, dot, flake, fleck, freckle,
   harlequin, iris, maculate, marble, marbleize, motley, mottle,
   pepper, polychrome, polychromize, rainbow, relieve, spangle, speck,
   speckle, splotch, spot, sprinkle, stigmatize, stipple, streak,
   striate, stripe, stud, tattoo, tessellate, variate, vary, vein