The Collaborative International Dictionary of English v.0.48:

Selfless \Self"less\, a.
   Having no regard to self; unselfish.
   [1913 Webster]

         Lo now, what hearts have men! they never mount
         As high as woman in her selfless mood.   --Tennyson.
   [1913 Webster]

WordNet (r) 3.0 (2006):

selfless
    adj 1: showing unselfish concern for the welfare of others [syn:
           altruistic, selfless] [ant: egocentric, egoistic,
           egoistical, self-centered, self-centred]

Moby Thesaurus II by Grady Ward, 1.0:

47 Moby Thesaurus words for "selfless":
   Olympian, altruistic, candid, charitable, committed, consecrated,
   considerate, dedicated, detached, devoted, disinterested,
   dispassionate, elevated, generous, high-minded, humble, impartial,
   impersonal, lofty, magnanimous, modest, neutral, open, sacrificing,
   self-abasing, self-abnegating, self-abnegatory, self-denying,
   self-devoted, self-effacing, self-forgetful, self-immolating,
   self-neglectful, self-neglecting, self-renouncing,
   self-sacrificing, self-unconscious, thoughtful, unacquisitive,
   unbiased, ungrudging, uninfluenced, unpossessive, unpretentious,
   unselfish, unsparing of self, unswayed