An isthmus (/ˈɪsməs, ˈɪsθməs/;[1] pl.: isthmuses or isthmi)[2] is a narrow piece of land connecting two larger areas across an expanse of water by which they are otherwise separated.[3] A tombolo is an isthmus that consists of a spit or bar, and a strait is the sea counterpart of an isthmus, a narrow stretch of sea between two landmasses that connects two larger bodies of water.