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

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

Cane Corsos are part of the mastiff family. —David Goodhue, Miami Herald, 17 Feb. 2026

But just reaching the elite, champions-only show is a major accomplishment in dogdom, especially for first-timers such as Joseph Carrero and his Neapolitan mastiff, Dezi. —CBS News, 4 Feb. 2026

But just reaching the elite, champions-only show is a major accomplishment in dogdom, especially for first-timers such as Joseph Carrero and his Neapolitan mastiff, Dezi. —Jennifer Peltz, Chicago Tribune, 3 Feb. 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