The Collaborative International Dictionary of English v.0.48:

Selflessness \Self"less*ness\, n.
   Quality or state of being selfless.
   [1913 Webster]

WordNet (r) 3.0 (2006):

selflessness
    n 1: the quality of unselfish concern for the welfare of others
         [syn: altruism, selflessness] [ant: egocentrism,
         egoism, self-centeredness, self-concern, self-
         interest]
    2: acting with less concern for yourself than for the success of
       the joint activity [syn: selflessness, self-sacrifice]