Altruism refers to actions undertaken for the concern and benefit of others at ones own expense.
"an "altruist" is someone who chooses between actions according to the criterion of others' welfare" - Eliezer Yudkowsky
Related tags and wikis: Shut up and multiply, Fuzzies, World Optimization, Effective Altruism, Cause Prioritization, Motivations, Psychology of Altruism, Ethics and Morality