The Collaborative International Dictionary of English v.0.48:

Unfair \Un*fair"\, a. [AS. unf[ae]ger unlovely. See Un- not,
   and Fair, a.]
   Not fair; not honest; not impartial; disingenuous; using or
   involving trick or artifice; dishonest; unjust; unequal.
   [1913 Webster]

         You come, like an unfair merchant, to charge me with
         being in your debt.                      --Swift.
   [1913 Webster] -- Un*fair"ly, adv. -- Un*fair"ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unfairly
    adv 1: in an unfair manner; "they dealt with him unfairly";
           "their accusations hit below the belt" [syn: unfairly,
           below the belt] [ant: clean, fair, fairly]