Caduceus,
symbolic staff surmounted by two wings and entwined by two snakes. The word derives from the ancient Greek karyx, meaning "herald." In ancient Greece the caduceus was carried by heralds and ambassadors as a badge of office and a mark of personal inviolability, because it was the symbol of Hermes, the messenger of the gods. According to Book IV of Virgil's Aeneid, the Greek god Apollo gave the staff to Hermes in return for the lyre. In Roman mythology the symbol is associated with the god Mercury. In recent centuries the caduceus has often been employed as an emblem for activities with which Hermes and Mercury were associated, such as communication or commerce. It has also sometimes been used to stand for the medical arts, apparently because of its similarity to a more common medicine-related symbol--the staff, or rod, of Asclepius, the Greek god of healing. The Asclepian staff is entwined by a single snake (see Aesculapian Snake. It is used as a symbol by organizations ranging from the American Medical Association, to the U.S. Air Force Medical Service, to the World Health Organization. Medical organizations using the caduceus as a logo are found mainly in the U.S.; they include the U.S. Army Medical Corps and the U.S. Public Health Service.