Noun

• S: (n) subject, case, guinea pig (a person who is subjected to experimental or other observational procedures; someone who is an object of investigation) "the subjects for this investigation were selected randomly"; "the cases that we studied were drawn from two different communities"
• S: (n) guinea pig, Cavia cobaya (stout-bodied nearly tailless domesticated cavy; often kept as a pet and widely used in research)