The building blocks of English

Affixes

opistho-

Behind; to the rear.

Greek opisthen, behind.

In medicine, opisthotonos (Greek tonos, tension) or opisthotonus is spasm of the muscles causing backward arching of the head, neck, and spine; in zoology, an opisthosoma (Greek sōma, body) is the abdomen of a spider or other arachnid; an opisthobranch (Greek brankhia, gills) is a member of a group of molluscs, the Opisthobranchia, which includes the sea slugs and sea hares, so called because their gills are placed well back on the body.