Self-sacrifice, n.
The act of sacrificing one's self, or one's interest, for others; self-devotion.
Shades of meaning
Fernald has no entry of its own for self-sacrifice; he lists it under self-abnegation.
Where he writes about it:
Self-sacrifice is the strongest and completest term of all, and contemplates the gift of self as actually made. — from self-abnegation
We speak of the self-sacrifice of Christ, where any other of the above terms would be feeble or inappropriate. — from self-abnegation