The Collaborative International Dictionary of English v.0.48:

Selfish \Self"ish\, a.
   1. Caring supremely or unduly for one's self; regarding one's
      own comfort, advantage, etc., in disregard, or at the
      expense, of those of others.
      [1913 Webster]

            They judge of things according to their own private
            appetites and selfish passions.       --Cudworth.
      [1913 Webster]

            In that throng of selfish hearts untrue. --Keble.
      [1913 Webster]

   2. (Ethics) Believing or teaching that the chief motives of
      human action are derived from love of self.
      [1913 Webster]

            Hobbes and the selfish school of philosophers.
                                                  --Fleming.
      [1913 Webster]

WordNet (r) 3.0 (2006):

selfish
    adj 1: concerned chiefly or only with yourself and your
           advantage to the exclusion of others; "Selfish men
           were...trying to make capital for themselves out of the
           sacred cause of civil rights"- Maria Weston Chapman [ant:
           unselfish]

The Devil's Dictionary (1881-1906):

SELFISH, adj.  Devoid of consideration for the selfishness of others.