guinea pig
From Longman Dictionary of Contemporary EnglishRelated topics: Animalsguinea pigˈguinea pig noun [countable] 1 HBAa small furry animal with short ears and no tail, which is often kept as a pet2 TEST/EXPERIMENTsomeone who is used in a scientific test to see how successful or safe a new product, system etc isOrigin guinea pig (1600-1700) Guinea, probably by mistake for Guiana, earlier name of Guyana