Atreus Syllabification: (A·tre·us)Pronunciation: /āˈtrēəs, ˈātro͞os/ Greek MythologyDefinition of Atreus the son of Pelops and father of Agamemnon and Menelaus. He quarreled with his brother Thyestes and invited him to a banquet at which he served up the flesh of Thyestes' own children. Atreus in other Oxford dictionaries Definition of Atreus in the British & World English dictionary