mastiff

noun

mas·​tiff ˈma-stəf 

: any of a breed of very large massive powerful smooth-coated dogs that are apricot, fawn, or brindle and are often used as guard dogs

Illustration of mastiff

Examples of mastiff in a Sentence

Recent Examples on the Web

About seven or eight o'clock in the morning, with his hoodie on and about six bull mastiffs coming out of a VW van. —Tommy McArdle, PEOPLE, 23 Sep. 2025

Located in the elegant Evasion Mont Blanc, there are nearly 250 miles of slopes spread over four mastiffs to ski here, and well, to plot. —Kathleen Rellihan, Outside, 5 Sep. 2025

Cane Corsos, an ancient Italian mastiff breed, are renowned for their sheer size and protective instincts. —Melissa Fleur Afshar, MSNBC Newsweek, 2 Sep. 2025

The Guinness World Record for most puppies in one litter belongs to Tia, a Neapolitan mastiff who gave birth to 24 puppies on Nov. 29, 2004, in Manea, U.K. —Kimberlee Speakman, People.com, 2 Sep. 2025

Word History

Etymology

Middle English mastif, from Medieval Latin mastivus, from Vulgar Latin *masuetivus, from Latin mansuetus tame — more at mansuetude

First Known Use

14th century, in the meaning defined above

Kids Definition

mastiff

noun

mas·​tiff ˈmas-təf 

: any of a breed of large powerful smooth-coated dogs often used as watchdogs and guard dogs