guinea pig

noun

1

: a small stout-bodied short-eared tailless domesticated rodent (Cavia porcellus) of South American origin often kept as a pet and widely used in biological research

called also cavy

2

: a subject of research, experimentation, or testing

Examples of guinea pig in a Sentence

He volunteered to act as a guinea pig in the experiment.

Recent Examples on the Web

Conrad Gessner, the sixteenth-century Swiss physician, naturalist, and linguist, and reputedly the first European to describe the guinea pig, the tulip, and the pencil, is also said to be the first to write extensively about the northern bald ibis. —Nick Paumgarten, The New Yorker, 10 Feb. 2025

So far, Sacramento SPCA has picked up a total of 17 animals, including nine dogs, three hamsters and three guinea pigs, Brent said. —Marcus D. Smith, Sacramento Bee, 18 Jan. 2025

Aitken also said that owners should always transport cats and small pets, like guinea pigs or bunnies in pet carriers. —John Mac Ghlionn, Newsweek, 13 Jan. 2025

In this era of NIL, and for-pay college athletics, Ewers is part pioneer, and part guinea pig. —Mac Engel, Fort Worth Star-Telegram, 11 Jan. 2025

Word History

First Known Use

1664, in the meaning defined at sense 1

Kids Definition

guinea pig

noun

1

: a small stocky rodent with short ears and a very short tail that is often kept as a pet and is used in biological research

2

: a person or thing experimented on

Medical Definition

guinea pig

noun

guin·​ea pig ˈgin-ē-ˌ 

: a small stout-bodied short-eared nearly tailless domesticated rodent of the genus Cavia (C. cobaya) often kept as a pet and widely used in biological research

called also cavy