Gr. Myth. a daughter of Agamemnon and Clytemnestra: she encourages her brother, Orestes, to kill their mother and their mother's lover, who together murdered Agamemnon
See Electra in American Heritage Dictionary 4
(ĭ-lĕkˈtrə)
noun Greek Mythology
A daughter of Clytemnestra and Agamemnon who with her brother Orestes avenged the murder of Agamemnon by killing their mother and her lover, Aegisthus.