Definition of prostomium in US English:

prostomium

noun

Zoology
  • In various invertebrates: a part of the body situated in front of or anterior to the mouth; especially (in annelid worms) the lobe or region anterior to the mouth (and to the first metameric segment), which in polychaetes contains the brain and bears eyes and sensory appendages.

Origin

Late 19th century; earliest use found in Henry Nicholson (1844–1899), biologist and geologist. From pro- + ancient Greek στόμα mouth + classical Latin -ium. Compare ancient Greek προστόμιον mouth, especially of a river, in Hellenistic Greek also joining of the lips.

Pronunciation

prostomium

/prəʊˈstəʊmɪəm/