— isthmoid , adj.
/is"meuhs/ , n. , pl. isthmuses, isthmi /-muy/ .
1. a narrow strip of land, bordered on both sides by water, connecting two larger bodies of land.
2. Anat. , Zool. a connecting, usually narrow, part, organ, or passage, esp. when joining structures or cavities larger than itself.
3. Ichthyol. the narrow fleshy area between the sides of the lower jaw of a fish.
[ 1545-55; isthmós neck (of land) ]