ostium
/ˈɒstɪəm/noun
(pl. ostia /-tɪə/)
1- Anatomy & Zoology an opening into a vessel or cavity of the body【剖, 动】口, 门, 孔。
1.1
- Zoology each of a number of pores in the wall of a sponge, through which water is drawn in【动】（海绵的）流入孔。
词源
early 17th cent.: from Latin, 'door, opening'.