ostiumPronunciation: /ˈɒstɪəm/Definition of ostium 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'ostium in other Oxford dictionaries Definition of ostium in the US English dictionary
