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Aegisthus, i, m., = Αἴγισθος, the son of Thyestes, who murdered Atreus and Agamemnon, with whose wife, Clytœmnestra, he lived in incest, and was finally slain by Orestes, Cic. N. D. 3, 38; Ov. R. Am. 161.
Hence, Pompey called Cæsar Ægisthus, on account of his adulterous connection with Mucia, Suet. Caes. 50.