Isthmian

Isthmian is the adjective pertaining to an isthmus.

It may also refer to:

Isthmian Games, one of the Panhellenic Games of Ancient Greece Isthmian League, a regional football league covering London and South East England Isthmian script, one of the Mesoamerican writing-systems Isthmian Steamship Company, a shipping company Isthmian Canal Commission, an American administration commission set up to oversee the construction of the Panama Canal