petrous

pet·rous   (pět'rəs)    adj.   Of, relating to, or resembling rock, especially in hardness; stony. Of or relating to the very dense, hard portion of the temporal bone that forms a protective case for the inner ear. [Middle English, from Old French petros, from Latin petrōsus, rocky, from petra, rock, from Greek petrā; see per-2 in Indo-European roots.]

Main Entry: pe·trous
Pronunciation: 'pe-tr&s, 'pE-
Function: adjective
: of, relating to, or constituting the exceptionally hard and dense portionof the human temporal bone that contains the internal auditory organs and is a pyramidal process wedged in at the base of the skull between the sphenoid and occipital bones with its lower half exposedon the surface of the skull and pierced by the external auditory canal

petrous pet·rous (pět'rəs)
adj.

1. Of stony hardness.

2. Of or relating to the dense hard portion of the temporal bone that forms a protective case for the inner ear.