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)


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  • You go in and complain of a sinus headache and he washes out your antrums for you.
    Raymond Chandler, 1953, The Long Goodbye, chapter 15

    September 5, 2009