paranasal sinus

[ păr′ə-nāzəl ]

n.

Any of the paired cavities, designated frontal, sphenoidal, maxillary, and ethmoidal, located in the bones of the face and lined by a mucous membrane continuous with that of the nasal cavity.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.