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
121 The inner projection of the temporal bone is known as the petrous process.
In man the internal ear (enclosed in the densest bone of the skull, named, from its density, "petrous") is a very complex organ.
"petrous" (_rocher_), developed from the nuchal plate; the ali - and orbito-sphenoids developed from the trabeculæ; the "cranial ethmoid"  developed from the facial plate; (2) the parietals, frontals and nasals formed from the "superior" protective plate; the "anterior" and
“The fracture proceeds from back to front across the petrous portions of both temporal bones.”
On its inner side is a small air chamber in the petrous portion of the temporal bone, called the cavity of the tympanum.
The third division of the organ is the internal ear, which is called the labyrinth; it is divided into the vestibule, three semicircular canals, and the cochlea: the whole are incased within the petrous portion of the temporal bone.
On removal of the crown of bone the bullet was discovered with the point turned backwards (having evidently undergone a partial ricochet turn) on the upper surface of the petrous bone, just above the lateral sinus.
With bone forceps or a fine saw, split open the petrous portion of the temporal bone and observe the cochlea and the semicircular canals.
Her intentionally looking aplomb into the rosary saleswoman's petrous countenance as she paid the money to her was a feigned attempt to project composure and went unnoticed.
This portion of the internal carotid begins at the bifurcation of the common carotid, opposite the upper border of the thyroid cartilage, and runs perpendicularly upward, in front of the transverse processes of the upper three cervical vertebræ, to the carotid canal in the petrous portion of the temporal bone.