mastiff

noun

mas·​tiff ˈma-stəf How to pronounce mastiff (audio)
: 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

Illustration of mastiff

Examples of mastiff in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
McIntire is going batty — in a good way — over attempts to investigate the elusive western mastiff. — Shi En Kim, AZCentral.com, 28 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 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 See All Example Sentences for mastiff

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

Time Traveler
The first known use of mastiff was in the 14th century

Browse Nearby Words

Masticura
mastiff
mastiff bat
See all Nearby Words

Cite this Entry

“Mastiff.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mastiff. Accessed 1 Sep. 2026.

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Kids Definition

mastiff

noun
mas·​tiff ˈmas-təf How to pronounce mastiff (audio)
: any of a breed of large powerful smooth-coated dogs often used as watchdogs and guard dogs

More from Merriam-Webster on mastiff

Britannica.com: Encyclopedia article about mastiff

Last Updated: - Updated example sentences
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