In an extreme case, altruism may become a synonym of selflessness which is the opposite of selfishness.
In a common way of living, it doesn't deny the singular nature of the subject, but realizes the traits of the individual personality in relation to the others, with a true, direct and personal interaction with each of them. It is focusing both on the single people and the whole community. In an (not only) christian practice, it is the law of love direct to the ego and his neighbour.
The word "altruism" was coined by the French philosopher Auguste Comte in French, as altruisme, for an antonym of egoism. He derived it from the Italian altrui, which in turn was derived from Latin alteri, meaning "other people" or "somebody else".
Altruism in biological observations in field populations of the day organisms can be defined as an individual performing an action which is at a cost to themselves (e.g., pleasure and quality of life, time, probability of survival or reproduction), but benefits, either directly or indirectly, another third-party individual, without the expectation of reciprocity or compensation for that action. Steinberg suggests a definition for altruism in the clinical setting, that is "intentional and voluntary actions that aim to enhance the welfare of another person in the absence of any quid pro quo external rewards".
Altruism can be distinguished from feelings of loyalty, in that whilst the latter is predicated upon social relationships, altruism does not consider relationships. Much debate exists as to whether "true" altruism is possible in human psychology. The theory of psychological egoism suggests that no act of sharing, helping or sacrificing can be described as truly altruistic, as the actor may receive an intrinsic reward in the form of personal gratification. The validity of this argument depends on whether intrinsic rewards qualify as "benefits". The actor also may not be expecting a reward.
The term altruism may also refer to an ethical doctrine that claims that individuals are morally obliged to benefit others. Used in this sense, it is usually contrasted with egoism, which claims individuals are morally obligated to serve themselves first.