Definition of "ostium" [‖Os•ti•um]

• A small opening or orifice, as in a body organ or passage. (noun)
• Any of the small openings or pores in a sponge. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "On the way from the second antechamber, called the ostium, to the atrium itself, Vinicius said, -- "Hast noticed that thee doorkeepers are without chains?""
• "Ante ostium similiter suspendunt filtrum opere polimitario variatum."
• "Socius meus accepit missale et crucem, clericus indutus supercilicio accepit thuribulum: sic accessimus ante dominum eius: et leuauerunt filtrum quod pendebat ante ostium vt nos posset videre."