/ Dictionary / Index T thornback: Meaning and Definition of Find definitions for: thorn•back Pronunciation: (thôrn'bak"), [key] — n. a skate, Raja clavata, of European waters, having short spines on the back and tail. a California ray, Platyrhinoidis triseriatus, belonging to the guitarfish group. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. thorn apple thornbush Related Content Daily Word Quiz: blithesome Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language