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

The Michigan State Police Jackson post said the three dogs, described as mixed-breed pit bull/mastiff dogs that escaped from a kennel, were returned to their owner's custody, pending the outcome of the investigation. — Paula Wethington, CBS News, 13 July 2026

Like that dutiful mastiff, this Urus is happiest when let off the leash. — Bryan Hood, Robb Report, 17 June 2026

Meanwhile, in 2004, a Neapolitan mastiff broke the Guinness World Record for most puppies after giving birth to 24. — Gabrielle Rockson, PEOPLE, 1 May 2026

Four chihuahuas were compared against three large dogs, a Tibetan mastiff, a Newfoundland and an English mastiff, along with their owner in the room. — Kate Perez, USA Today, 5 Mar. 2026

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