The scientific name of the common species is Cavia porcellus, with porcellus being Latin for "little pig". Cavia is New Latin; it is derived from cabiai, the animal's name in the language of the Galibi tribes once native to French Guiana. Paradoxically, breeders tend to use the more formal "cavy" to describe the animal, while in scientific and laboratory contexts it is far more commonly referred to by the more colloquial "guinea pig".
Guinea pigs are large for rodents, weighing between 700 and 1200g (1.5-2.5 pounds), and measuring between 20 and 25 cm (8–10 inches) in length. They typically live an average of four to five years, but may live as long as eight years.