Vestibulum

·noun A cavity into which, in certain bryozoans, the esophagus and anus open.

vestibulum
vestĭbŭlum, i, n. [perh. for vesti-bulum, kindr. with Sanscr. vas, habitare, commorari; cf. Vesta], ...

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.
vestibulum
vestibulum ī, n 2 VAS-, an enclosed space before a house, fore-court, entrance-court, vestibule : ...

An Elementary Latin Dictionary