"protection," 1793, from L. ægis, from Gk. Aigis, the shield of Zeus, said by Herodotus to be related to aix (gen. aigos) "goat," from PIE *aig- "goat" (cf. Skt. ajah, Lith. 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.