Pronunciation: (al"trOO-is'tik), [key]
1. unselfishly concerned for or devoted to the welfare of others (opposed to egoistic).
2. Animal Behav.of or pertaining to behavior by an animal that may be to its disadvantage but that benefits others of its kind, often its close relatives.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.