a. [ L. Isthmius, Gr. &unr_;. See Isthmus. ] Of or pertaining to an isthmus, especially to the Isthmus of Corinth, in Greece. [ 1913 Webster ]

Isthmian games (Gr. Antiq.), one of the four great national festivals of Greece, celebrated on the Isthmus of Corinth in the spring of every alternate year. They consisted of all kinds of athletic sports, wrestling, boxing, racing on foot and in chariots, and also contests in music and poetry. The prize was a garland of pine leaves. [ 1913 Webster ]

a. Extending across an isthmus, as at Suez or Panama. [ Webster 1913 Suppl. ]