Altruistic
/ˌæltruˈɪstɪk/ adjective easyShowing a genuine concern for the well-being of others, often at some cost to oneself.
The volunteer's altruistic decision to donate a kidney to a stranger amazed her coworkers.
Memory Trick
Altruistic contains 'altru,' close to the Latin root for 'other' — altruistic people put others first, not themselves.