Protection: a child whose welfare is now under the aegis of the courts. Sponsorship; patronage: a concert held under the aegis of the parents' association. Guidance, direction, or control:"the Mamelukes, the warrior caste that ruled Egypt under the distant aegis of the Turkish sultan"(David A. Bell). Greek Mythology The goatskin shield or breastplate of Zeus or Athena. Athena's shield carried at its center the head of Medusa.