metastomium
/ˌmɛtəˈstəʊmɪəm/Zoology
noun
Originally: the part of the head of a metameric invertebrate that is located behind the mouth. Later also: the body of an annelid, comprising the segments between the head and the pygidium.
Origin
Late 19th century; earliest use found in Ray Lankester (1847–1929), zoologist. From meta- + -stomium.