from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A cavity or chamber, especially one in a bone.
- n. Either of the sinuses in the bones of the upper jaw, opening into the nasal cavity.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A bodily cavity, especially one having bony walls, especially one in the sinuses.
from the GNU version of the Collaborative International Dictionary of English
- n. A cavern or cavity, esp. an anatomical cavity or sinus.
from The Century Dictionary and Cyclopedia
- n. A name of various cavities in the body, but when used alone signifying the antrum Highmorianum (cavity of Highmore, also called sinus maxillaris), a cavity in the superior maxillary bone, lined with mucous membrane and communicating with the middle meatus of the nose.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a natural cavity or hollow in a bone
Late Latin, cavity in the body, from Latin, cave, from Greek antron.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Latin antrum, from Ancient Greek ἄντρον (antron, "cave"). (Wiktionary)