/ Dictionary / Index B blackthorn: Meaning and Definition of Find definitions for: black•thorn Pronunciation: (blak'thôrn"), [key] — n. a shrub or tree of the genus Crataegus, as C. calpodendron. a walking stick made of a blackthorn tree or shrub. Also calleda much-branched, thorny, Old World shrub, Prunus spinosa, having white flowers and small plumlike fruits. See Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: blackthorn (Thesaurus) black tea black tie Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language