The Collaborative International Dictionary of English v.0.48:

Self-abnegation \Self`-ab`ne*ga"tion\, n.
   Self-denial; self-renunciation; self-sacrifice.
   [1913 Webster]

WordNet (r) 3.0 (2006):

self-abnegation
    n 1: renunciation of your own interests in favor of the
         interests of others [syn: abnegation, self-abnegation,
         denial, self-denial, self-renunciation]