Definition of metastomium in US English:

metastomium

noun

Zoology
  • 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.

Pronunciation

metastomium

/ˌmɛtəˈstəʊmɪəm/