Teratology: invented in the nineteenth century, by Etienne and Isidore Geoffroy Saint-Hilaire, teratology is a now seldom-used term for the study of human monsters. Monsters was also a term used by the medical profession to describe people afflicted by a wide variety of conditions, including dwarves, giants, hermaphrodites, Siamese twins, midgets, and men and women born without arms and or legs.