Altruism refers to a motive to increase another's welfare without conscious regard for one's self -interests.
Altruism is the practice of charity, being particularly helpful to other people with little view to being rewarded for one's efforts. Altruism is the doctrine that says one's actions ought to further the interests or good of other people, if necessary to the exclusion of one's own interests. The term was coined by Auguste Comte, the French founder of positivism. Altruism is distinguished from ethical egoism, according to which one's actions ought to further one's own interests.
Other /More definition:
Altruism refers to a selfless concern for the welfare of others that is expressed through pro-social acts such as sharing, cooperating, comforting others, or helping.
Moreover, Altruism is voluntary actions that help or benefit another person or group of people without the actor’s anticipation of external rewards. Such actions often entail some cost, self-sacrifice, or risk on the part of the actor.
In this defense mechanism, individuals learn to become helpful to avoid feeling helpless. They learn that they can satisfy their own egos as well as the demands of society.
Lexicon of Psychology - Terms, Treatments, Biographies,