Imbecile was a medical category of people with moderate to severe intellectual disability, as well as a type of criminal.[1][2] The term arises from the Latin word imbecillus, meaning weak, or weak-minded. It included people with an IQ of 26–50, between “moron” (IQ of 51–70) and “idiot” (IQ of 0–25).[3]The meaning was further refined into mental and moral imbecility.[4][5] The concepts of “moral insanity”, “moral idiocy”,” and “moral imbecility”, led to the emerging field of eugenic criminology, which held that crime can be reduced by preventing “feeble-minded” people from reproducing.[6][7]

“Imbecile” as a concrete classification was popularized by psychologist Henry H. Goddard[8] and was used in 1927 by United States Supreme Court Justice Oliver Wendell Holmes, Jr. in his ruling in the forced-sterilization case Buck v. Bell, 274 U.S. 200 (1927).[9]

The concept is closely associated with psychology, psychiatry, criminology, and eugenics. However, the term imbecile quickly passed into vernacular usage as a derogatory term, and fell out of professional use in the 20th century[10] in favor of mental retardation.