(Ἴσθμιος), i. e. the god worshipped on the Isthmus (of Corinth), a surname of Poseidon, in honour of whom the Isthmian games were celebrated. (Paus. 2.9.6 )
[L.S]634
A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890