guinea pig

noun
  1. A small, domesticated rodent of the species Cavia porcellus, often kept as a pet and used in scientific research. noun
    She has a guinea pig named Charlie that she keeps in a cage in her room.
    Guinea pigs are known for their gentle nature and are popular pets for children.
  2. A person or thing used as a subject for experimentation or research. noun
    He felt like a guinea pig when the new software was tested on him first.
    The volunteers were treated as guinea pigs in the early trials of the vaccine.