It is a voice that means "rough, uneducated, unskilled person." It comes from Jonathan Swift's novel Travels into Several Remote Nations of the World, in Four Parts. By Lemuel Gulliver , First a Surgeon , and then a Captain of Several Ships . ("Travels through some remote nations of the world, in four parts. By Lemuel Gulliver, first a surgeon and then a captain of several ships. " ) , where the yahoos are characters who are described in the last part as beings similar to humans but who lost all trait of civilization, maintaining their worst instincts, and who are used as domestic animals by a breed of cultured and intelligent horses. Although after living with horses, Gulliver's entire eighteenth-century society became similar to a yahoo group.