(Διεύχης), a Greek physician, who lived probably in the fourth century B. C., and belonged to the medical sect of the Dogmatici. (Galen, de Ven. Sect. adv. Erasistr. 100.5, vol. xi. p. 163; comp. Id. de Simplic. Medical. Temper. ac Facult. vi. prooem. vol. xi. p. 795, de Meth. Med. 1.3, 7.3, vol. x. pp. 28, 462, Comment. in Hippocr. "de Nat. Hom." 2.6, vol. xv. p. 136.) He was tutor to Numenius of Heraclea (Athen. 1.5.8), and is several times quoted by Pliny. (H. N. 20.15, 33, 73, 23.29, 24.92.) He wrote some medical works, of which nothing but a few fragments remain. (Ruf. Ephes., ed. Matthaei ; XXI Vet. Medic. Graec. Opusc. ed. Matthaei ; C. G. Kühn, Additam. ad Elench. Medic. Vet. a J. A. Fabric. exhibit. fasc.xiii. p.6.)