/ Dictionary / Index T thorn apple: Meaning and Definition of Find definitions for: thorn' ap"ple Pronunciation: (thôrn), [key] any poisonous plant belonging to the genus Datura, of the nightshade family, the species of which bear capsules covered with prickly spines, esp. the jimson weed, D. stramonium. the fruit of certain hawthorns of the genus Crataegus. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. thorn thornback Related Content Daily Word Quiz: opulent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language