The Collaborative International Dictionary of English v.0.48:

Unbiased \Un*bi"ased\ ([u^]n*b[imac]"ast), a. [Pref. un- not +
   biased.]
   Free from bias or prejudice; unprejudiced; impartial. --
   Un*bi"ased*ly, adv. --Un*bi"ased*ness, n.
   [1913 Webster] Unbid

The Collaborative International Dictionary of English v.0.48:

Unbiased \Unbiased\
   See biased.

WordNet (r) 3.0 (2006):

unbiased
    adj 1: characterized by a lack of partiality; "a properly
           indifferent jury"; "an unbiasgoted account of her family
           problems" [syn: indifferent, unbiased, unbiassed]
    2: without bias [syn: unbiased, unbiassed]

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "unbiased":
   Olympian, aloof, candid, detached, disinterested, dispassionate,
   equal, equitable, evenhanded, fair, impartial, impersonal,
   indifferent, just, lofty, neutral, objective, selfless, uncolored,
   undazzled, uninfluenced, uninterested, unjaundiced, unprejudiced,
   unprepossessed, unselfish, unswayed