noun. A small opening or orifice, as in a body organ or passage.

noun. Any of the small openings or pores in a sponge, through which water is drawn in.

noun. An opening or entrance; a mouth; an os.

noun. In zoology: In sponges, the opening of an incurrent canal.

noun. An opening; a passage.

noun. A small opening or orifice, as in a body organ or passage.

noun. Any of the small openings or pores in a sponge.

"On the way from the second antechamber, called the ostium, to the atrium itself, Vinicius said, -- "Hast noticed that thee doorkeepers are without chains?""

gastric ostium  ostium tubæ  

aedis  bellum  censet  exitum  fratrem  

opening  passage