1. of or like rock; hard; stony
Webster’s New World College Dictionary, Fourth Edition, compiled by the
editors of Webster’s New World Dictionaries. Copyright © 2010 by Houghton
Mifflin Harcourt. Published by Houghton Mifflin Harcourt. All rights reserved.
Word origin of 'petrous'L petrosus, rocky < petra, rock < Gr; (sense 2) ML petrosus