n., pl., -ti·a (-tē-ə).
- A small opening or orifice, as in a body organ or passage.
- Any of the small openings or pores in a sponge.
[Latin ōstium, door, opening, from ōs, mouth.]
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
