Simple Definition of guinea pig

from our Learner's Dictionary

guinea pig

noun

plural guinea pigs

1

: a small animal that is often kept as a pet

2

: a person or thing used for testing something

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

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“Guinea pig.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/guinea%20pig. Accessed 22 Jun. 2026.

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