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

Police allege that after shooting his father, the teen took off in the family vehicle, a Rivian SUV, with the family dog, a French mastiff. — Dejanay Booth-Singleton, CBS News, 11 Aug. 2026

Protecting his flock is a constant struggle, one aided by a huge Spanish mastiff that was keeping the sheep in a tight circle and barking loudly. — Simon Willis, Travel + Leisure, 4 Aug. 2026

Jayne Hardman’s struggles with her nose began in 2012, when her mastiff jumped up and accidentally hit her in the face. — Cara Lynn Shultz, PEOPLE, 30 July 2026

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