Though altruism has been of a strategic part in the formation and development of Islamic civilization, it has not been study separately and in detail. Muslim scholars, in particular those in moral and mysticism, have spoken of its what-ness. Predecessors have regarded donation in the state of need as its essential part of meaning while those of latter-day has intended by the word preferring others to oneself. Of the meanings, the former has been more accepted. Yet, these definitions would not be able to include such cases as jihad, martyrdom and sacrificing. The study, having studied and mentioned the two definitions critically and with a historical approach, has given a more comprehensive definition as: a communicative action in which a person with good intention prefers another one, being in need or not, to himself/herself for something of his/her needs or concern.