n. 1. Unselfish concern for the welfare of others; selflessness. 2. Zoology Instinctive behavior that is detrimental to the individual but favors the survival or spread of that individual's genes, as by benefiting its relatives. [French altruisme, probably from Italian altrui, someone else, from Latin alter, other; see al-1 in the Appendix of Indo-European roots.] altru·ist n. al′tru·istic adj. al′tru·isti·cal·ly adv. |
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