(Εὐθύδημος).
1. A sophist, was born at Chios, and migrated with his brother Dionysodorus to Thurii in Italy. Being exiled thence, they came to Athens, where they resided many years. The pretensions of Euthydemus and his brother are exposed by Plato in the dialogue which bears the name of the former. A sophism of Euthydemus, as illustrating the " fallacy of composition," is mentioned by Aristotle. (Plat. Euthydemus, Cratyl. p. 386; Arist. Rhet. 2.24.3, Soph. El. 20; Ath. xi. p. 506b; Sext. Emp. ad v. Math. 7.13.)