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

Luckily, the cubs were only after the dry food and did not hurt the guinea pigs. — Nicole Comstock, CBS News, 15 Sep. 2026

The Chambers home would serve as a guinea pig for the Historic House Relocation Project. — Nicola Twilley, New Yorker, 27 Aug. 2026

The squeals from the little piggies about to eat lettuce and other vegetation often spark laughter, while others cuddle and comfort some of the guinea pigs. — ABC News, 18 Aug. 2026

The fire resulted in the loss of Smothermon’s other grandson, two dogs and dozens of guinea pigs. — Kimberlee Kruesi, Fortune, 18 Aug. 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