- Anatomy, Zoology. a small opening or orifice, as at the end of the oviduct.
- Zoology. one of the tiny holes in the body of a sponge.
Origin of ostium
First recorded in 1655–65, ostium is from the Latin word ōstium entrance, river mouth
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for ostium
Here in the door-way, or ostium, we stop to note the "Salve!"Historic Boys
Elbridge Streeter Brooks
The porter, who sat in a niche of the entrance-corridor (ostium).Quintus Claudius, Volume 1 of 2
This will bring the anterior wall of the sinus with its ostium into view.
Double doors admitted the visitor to the entrance-hall, or ostium.Stories of the Olden Time
With the help of cocaine the ostium can then be enlarged with various instruments.
- any of the pores in sponges through which water enters the body
- any of the openings in the heart of an arthropod through which blood enters
- any similar opening
C17: from Latin: door, entrance
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
- A small opening or orifice, as in a body organ.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.