egis

"protection," 1793, from Latin aegis, from Greek Aigis, the name of the shield of Zeus, said by Herodotus to be related to aix (genitive aigos) "goat," from PIE *aig- "goat" (cf. Sanskrit ajah, Lithuanian ozys "he-goat"), as the shield was of goatskin. Athene's aigis was a short goat-skin cloak, covered with scales, set with a gorgon's head, and fringed with snakes. The exact use and purpose of it is not now clear.