Motive or motif, in music, a short phrase or passage of two or more notes and repeated or elaborated throughout the composition. The term is usually used synonymously with figure. A special ki...

Enkephalin, one of several naturally occurring morphinelike substances (endorphins) released from nerve endings of the central nervous system and the adrenal medulla. They act as analgesics an...

Ctesibius, fl. 2d cent. B.C., Alexandrian Greek inventor. He reputedly was the first to discover and apply the expansive power of air as a motive force. Among the inventions ascribed to him ar...

Altruism, concept in philosophy and psychology that holds that the interests of others, rather than of the self, can motivate an individual. The term was invented in the 19th cent. by the Fren...

Egoism, in ethics, the doctrine that the ends and motives of human conduct are, or should be, the good of the individual agent. It is opposed to altruism, which holds the criterion of morality...

Kleptomania [Gr.,=craze for stealing], irresistible compulsion to steal, motivated by neurotic impulse rather than material need. No specific cause is known. The condition is considered genera...

Will, in philosophy and psychology, term used to describe that which is alleged to stimulate the motivation of purposeful activity. It is characteristic of the will that it can be observed onl...

Suicide [Lat.,=self-killing], the deliberate taking of one's own life. Suicide may be compulsory, prescribed by custom or enjoined by the authorities, usually as an alternative to death at the...

Thirty Years War, 1618–48, general European war fought mainly in Germany. There were many territorial, dynastic, and religious issues that figured in the outbreak and conduct of the war. The e...

Exploration, travel to a part of the earth that is relatively unknown to the traveler's culture, historically often motivated by a desire for colonization, conquest, or trade.See also space ex...