Anat. an opening or orifice
Origin of ostiumClassical Latin ostium: see ostiary
- A small opening or orifice, as in a body organ or passage.
- Any of the small openings or pores in a sponge, through which water is drawn in.
Origin of ostiumLatin ōstium, door, opening, from ōs, mouth; see ōs- in Indo-European roots.