a small animal covered in fur with rounded ears, short legs, and no tail, often kept as a pet by children

Guinea pigs need a covered area with bedding where they can shelter.

Many young girls have to make do with a guineapig or a hamster when what they really want is a pony.

a person used in a scientific test, for example to discover the effect of a drug on humans

They're asking for students to be guinea pigs in their research into the common cold. 他们正在找学生来做他们研究普通感冒的实验对象。