prostomium

noun

pro·​sto·​mi·​um prō-ˈstō-mē-əm 

plural prostomia prō-ˈstō-mē-ə 

: the portion of the head of an annelid worm (such as an earthworm) that is situated in front of the mouth

prostomial

prō-ˈstō-mē-əl 

adjective

Word History

Etymology

New Latin, from Greek pro- + stoma mouth — more at stomach entry 1

First Known Use

1870, in the meaning defined above