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 upstairs neighbors had two mastiffs who were left home all day and who barked incessantly and scratched at the floor of their kennel. — Meghan O’Gieblyn, The New York Review of Books, 5 Sep. 2026

McIntire is going batty — in a good way — over attempts to investigate the elusive western mastiff. — Shi En Kim, AZCentral.com, 28 Aug. 2026

The family dog, a French mastiff, has been recovered and was not harmed. — Tresa Baldas, Freep.com, 19 Aug. 2026

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

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