rock-ribbed (r?k?r?bd?)adj.1. Having rocks or rock outcroppings; rocky.2. Firm and unyielding, especially with regard to one’s principles, loyalties, or beliefs: a rock-ribbed conservative.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.rock-ribbed adj US firm; uncompromising Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014rock?-ribbed` adj. 1. having ribs or ridges of rock. 2. unyielding; confirmed and uncompromising. [1770?80] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.