s. LGPN

(also Ἰθμός SIG 507 (Delph., iii BC), cf. ἰσθμός) ὁ (ἡ in Pi., as O. 7.81, 8.48), the Isthmus of Corinth, Hdt. 8.40, etc. ; Ἰσθμοῦ δειράς, αὐχὴν Ἰσθμοῦ, Pi. I. 1.9, B. 2.7; dat. Ἰσθμῷ prob. f.l. for Ἰσθμοῖ in Th. 5.18, AP 13.15; but ἐν Ἰσθμῷ correctly in Hdt. 9.27, 81.
narrow ridge, of the Caucasus, between Caspian and Euxine, Arist. Mu. 393b25, D.P. 20. of the sea, strait, narrow channel, Inscr.Délos ll.cc., App. Hann. 34. (Perh. fr. εἶμι (ibo), cf. ἴθμα, εἰσίθμη, and the spellings Ἰθμός (supr.), Ἰθμονίκα IG 4.951.10.)

Place, proper name

• the fortified neck of land joining the Greek mainland to the Peloponnese. (TOPOS text)