/ Dictionary / Index M mastiff: Meaning and Definition of Find definitions for: mas•tiff Pronunciation: (mas'tif, mä'stif), [key] — n. one of a breed of large, powerful, short-haired dogs having an apricot, fawn, or brindled coat. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: mastiff (Thesaurus) masticatory mastiff bat Related Content Daily Word Quiz: panacea Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language