Aegis

Webster's Dictionary

(n.) A shield or protective armor; - applied in mythology to the shield of Jupiter which he gave to Minerva. Also fig.: A shield; a protection.

The Nuttall Encyclopedia

A goat's skin), the shield of Zeus, made of the hide of the goat Amalthea ( q. v .), representing originally the storm-cloud in which the god invested himself when he was angry; it was also the attribute of Athena, bearing in her case the Gorgon's head.