guinea pig
Americannoun
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a short-eared, tailless rodent of the genus Cavia, usually white, black, and tawny, commonly regarded as the domesticated form of one of the South American wild species of cavy: often used in scientific experiments or kept as a pet.
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Informal. the subject of any sort of experiment.
I've volunteered as a guinea pig in several clinical trials.
noun
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a domesticated cavy, probably descended from Cavia porcellus, commonly kept as a pet and used in scientific experiments
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a person or thing used for experimentation
Other Word Forms
Noun Inflected Forms
Etymology
Origin of guinea pig
First recorded in 1655–65
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.
You don’t want your guest to be a guinea pig.
From Los Angeles Times ● Jul. 23, 2026
Criw Compostio picks up waste, as well as wood shavings from a carpentry business and used rabbit and guinea pig bedding from pet owners, twice a week.
From BBC ● Jul. 19, 2026
"I wouldn't want to be the first guinea pig," as "it's not so easy to have everything just smooth" like Apple has managed to do with its laptops.
From Barron's ● Jun. 1, 2026
As he buttoned up a professional baseball uniform for the first time in his life, he understood that he was becoming the guinea pig in an experiment that has the whole industry watching.
From The Wall Street Journal ● Nov. 25, 2025
Maybe he’d be tucked into the warmth of his bed, listening to Gulliver’s cage rattle as the guinea pig drank his water.
From "Hello, Universe" by Erin Entrada Kelly
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
