cavy

noun

1. A tailless rodent of the family Caviidae and the genus Cavia, with short ears and larger than a hamster; the species Cavia porcellus is often kept as a pet.
2. A rodent of any of several species within the family Caviidae.
3. A living experimental subject.“He became a human guinea pig and was paid by the company.”
4. A professional company director, without time or real qualifications for the duties.