Altruism
Etymology
A coinage: the French philosopher Auguste Comte minted "altruisme" in the 1830s from Italian "altrui" (of or to others), which traces to Latin "alter" (other). He built it deliberately as the opposite of "egoism," to name living for others. English borrowed it within a couple of decades, and biology later adopted it for costly other-helping behavior in animals.
noun · /AL-troo-iz-uhm/
Concern for the welfare of others as an end in itself, even at cost to oneself.
What it names
Use it for genuinely other-directed motivation — acting for another’s good rather than for reward, reputation, or reciprocity.
Example
Whether pure altruism exists at all, or always hides some payoff, is a question biologists still argue.
Related idea
Selflessness describes the absence of self-regard; altruism describes the positive orientation toward others’ good. Biologists further split "altruism" into behavior that helps others at a fitness cost — a narrower, testable sense than the everyday one.