ostium

 
Pronunciation: /ˈɒstɪəm/

noun (plural ostia /ˈɒstɪə/)

Anatomy & Zoology
  • an opening into a vessel or cavity of the body.
  • Zoology each of a number of pores in the wall of a sponge, through which water is drawn in.

Origin:

early 17th century: from Latin, 'door, opening'