Why are guinea pigs called cavies?

The word "cavy" comes from the Tupi language, an indigenous language spoken in Brazil. The Tupi word "caví" referred to these small rodents.

When Europeans encountered these animals in South America, they adopted the Tupi word, which eventually evolved into "cavy" in English.

So, while "guinea pig" is the more common name, the word "cavy" is a direct link to the animal's original South American origins.