aegis, in Greek mythology, weapon of Zeus and Athena. It possessed the power to terrify and disperse the enemy or to protect friends. The aegis was usually described as a garment made of goatskin slung over the shoulder or as a piece of armor. The aegis of Athena was a breastplate covered with goatskin and bordered with snakes, bearing in the center the head of the Gorgon Medusa.

In ancient Greece, the leather cloak or breastplate associated with Zeus. It was worn most prominently by Zeus's daughter Athena (whose aegis bore the head of Medusa) but occasionally also by other gods (e.g., Apollo in the Iliad).

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