mastiff

American

[mas-tif, mah-stif] / ˈmæs tɪf, ˈmɑ stɪf /

noun

one of a breed of large, powerful, short-haired dogs having an apricot, fawn, or brindled coat.

mastiff British

/ ˈmæstɪf /

noun

an old breed of large powerful short-haired dog, usually fawn or brindle with a dark mask

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of mastiff

1300–50; Middle English mastif, perhaps extracted from Anglo-French masti ( n ) s (taken as *mastifs ), plural of Old French mastin < Vulgar Latin ( canis ) *ma ( n ) suētīnus, derivative of Latin mansuētus tame, mild ( see mansuetude)

Compare meaning

How does mastiff compare to similar and commonly confused words? Explore the most common comparisons:

mastiff vs. bullmastiff

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Some large guardian dogs showed high wolf ancestry, while others, including the Neapolitan mastiff, bullmastiff, and St. Bernard, showed none.

From Science Daily • Nov. 29, 2025

They joked about sending their mastiff to the door next time.

From Salon • Jun. 8, 2025

Previously, the Lowe family had a bull mastiff rescue, Gus, who bit son Samuel in 2023 after the boy tried to bend down and pet him.

From Los Angeles Times • Mar. 19, 2025

We were sitting in his studio while Kaya, his enormous Tibetan mastiff, weaved through our legs.

From Slate • Feb. 18, 2025

Stannis Baratheon with a grievance was like a mastiff with a bone; he gnawed it down to splinters.

From "A Dance with Dragons" by George R. R. Martin

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023