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English definition of “guinea pig”

guinea pig

noun [C]  /ˈɡɪn·i ˌpɪɡ/ us  
a small, furry animal with rounded ears, short legs, and no tail, often kept as a pet and for use in scientific experiments fig. A guinea pig is also a person used in a test, esp. one to discover how effective a new drug or process is: Her own son accused her of having used him as a guinea pig to test her theories about the education of children.
(Definition of guinea pig from the Cambridge Academic Content Dictionary © Cambridge University Press)
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