/ Dictionary / Index R rock crab: Meaning and Definition of Find definitions for: rock' crab" Pronunciation: [key] any of several crabs that live along rocky beaches, esp. those of the genus Cancer, as C. irroratus, of the eastern coast of North America, having the rear legs modified for running. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Rock Cornish rock cress Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language