The Collaborative International Dictionary of English v.0.48:

Bias \Bi"as\, v. t. [imp. & p. p. Biased (b[imac]"ast); p. pr.
   & vb. n. Biasing.]
   To incline to one side; to give a particular direction to; to
   influence; to prejudice; to prepossess.
   [1913 Webster]

         Me it had not biased in the one direction, nor should
         it have biased any just critic in the counter
         direction.                               --De Quincey.
   [1913 Webster]

WordNet (r) 3.0 (2006):

biased
    adj 1: favoring one person or side over another; "a biased
           account of the trial"; "a decision that was partial to
           the defendant" [syn: biased, colored, coloured,
           one-sided, slanted]

Moby Thesaurus II by Grady Ward, 1.0:

88 Moby Thesaurus words for "biased":
   across, antiblack, aslant, aslope, athwart, atilt, bendwise, bent,
   bevel, beveled, bias, biaswise, canting, careening, catercorner,
   catercornered, chauvinistic, colored, cooked, crossways, crosswise,
   diagonal, disposed, distorted, doctored, doctrinaire, dogmatic,
   garbled, inclinational, inclinatory, inclined, inclining,
   influenced, interested, involved, jaundiced, kittycorner,
   know-nothing, leaning, listing, misquoted, misrepresented,
   nonobjective, one-sided, opinionated, out of plumb, out of square,
   partial, partisan, perverted, pitched, predisposed, prejudiced,
   prepossessed, racist, raking, recumbent, sexist, shelving, shelvy,
   sideling, sidelong, slant, slanted, slanting, slantways, slantwise,
   sloped, sloping, strained, superpatriotic, swayed, tendentious,
   thwart, tilted, tilting, tipped, tipping, tipsy, tortured,
   transverse, twisted, ultranationalist, undetached, undispassionate,
   unneutral, warped, xenophobic