/ Dictionary / Index B bull thistle: Meaning and Definition of Find definitions for: bull' this"tle Pronunciation: [key] a tall, spiny thistle, Cirsium vulgare, having heads of pink to purple flowers: a common weed in North America. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. bull terrier bull tongue Related Content Daily Word Quiz: blanch Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language