A domestic species of rodent originating from South America, related to the capybara. The guinea pig is tailless and herbivorous, with a stout, "potato-like" body shape and a size approximately twice that of a common rat. To the uninitiated, the guinea pig may resemble an oversized hamster.
Guinea pigs are highly vocal rodents and are noted for making a characteristic "wheek" sound when excited or hungry. This sound is rendered as "pui" in Japanese onomatopoeia.
The scientific name of the species is Cavia porcellus. It is sometimes also called "cavy" by breeders and owners. Guinea pigs were frequently used as experimental animals in research; hence the word "guinea pig" is often also used metaphorically to refer to experimental subjects.
