from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Of, relating to, or resembling rock, especially in hardness; stony.
  • adj. Of or relating to the very dense, hard portion of the temporal bone that forms a protective case for the inner ear.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. Resembling rock or stone in its hardness
  • adj. Of the dense portion of the temporal bone that protects the inner ear.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Like stone; hard; stony; rocky.
  • adj. Same as Petrosal.

from The Century Dictionary and Cyclopedia

  • Like stone in hardness; stony; rocky.
  • Pertaining to the part of the temporal bone so called; petrosal: as. a petrous vein or sinus; a petrous ganglion.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. (of bone especially the temporal bone) resembling stone in hardness


Middle English, from Old French petros, from Latin petrōsus, rocky, from petra, rock, from Greek petrā.
(American Heritage® Dictionary of the English Language, Fourth Edition)
From the Greek petra, rock. (Wiktionary)



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