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

Other small mammals like ferrets, degus, sugar gliders, chinchillas, gerbils, hamsters, guinea pigs, rats and mice are all allowed as pets. —Stephen Underwood, Hartford Courant, 7 Apr. 2026

Care for guinea pigs, drive the bus, make a smoothie and more. —Denise Petski, Deadline, 6 Apr. 2026

That’s led to a generation of kids being treated as Big Tech guinea pigs and falling student achievement scores. —Abby McCloskey, Boston Herald, 5 Apr. 2026

For eight years, Ruth has cared for and rehabilitated non-native exotic animals like bearded dragons, guinea pigs, sugar gliders and leopard geckos in hopes of one day finding them a forever home. —Julian Camejo, Miami Herald, 4 Apr. 2026

Word History

First Known Use

1664, in the meaning defined at sense 1

Rhymes for guinea pig

• whirligig
• big
• brig
• brigg
• dig
• fig
• gig
• jig
• mig
• prig
• rig
• sprig

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. porcellus) often kept as a pet and widely used in biological research

called also cavy