Aegis is a Greek word (αἰγίς) used also in Latin. (say 'EEJ-iss', IPA: /ˈiːdʒ ɪs/). It originally meant 'a shield', or defensive weapon (see below). It is used mostly these days with a more figurative meaning: '[with the] protection [of]', '[under the] auspices [of]', '[within the] sphere of influence [of]': most generally, aegis can be seen as the equivalent of the more modern metaphor 'umbrella'. An individual, for example, may act under the aegis of an institution, as MPs, under the aegis of parliamentary privilege, may make statements in the House of Commons that would render them liable to being sued outside it, or someone may work under the aegis of a more powerful sponsor; troops may advance under the aegis of air cover. (There is a family of missile systems called 'Aegis' carried on board naval vessels for air defence, including an anti-missile 'Aegis Ballistic Missile Defense System'. It is a US weapons system, used in many allied navies.)
- Further etymological description: "aegis, divine attribute, represented as a large all‐round bib with scales, fringed with snakes' heads and normally decorated with [the image of a gorgon's head]. In Homer Zeus' epithet ‘aegis‐holding’, and the story that the aegis was given to him by Hephaestus suggests a primary association with Zeus, who lends it to Apollo. It is unclear whether Athena's aegis is also borrowed. In post‐Homeric times the aegis is most closely associated with Athena, who is commonly shown wearing it over her dress. In the Iliad the aegis is ageless and immortal, with a hundred tassels, and it is decorated with (a representation of) the Gorgon's face. Its shaking by Zeus or Apollo brings victory to the side the god supports and fear to its enemies. It protects from attack; not even Zeus' thunderbolt can break it" (Roberts, 2007).