OSTIUM

[ 'ɒstɪəm ]

■ noun ( plural ostia 'ɒstɪə )

1》 Anatomy & Zoology an opening into a vessel or cavity of the body.

2》 Zoology each of a number of pores in the wall of a sponge, through which water is drawn in.

Origin

C17: from L., 'door, opening'.