Huh! I wonder where he fits in?

In the 19th and early 20th centuries, "imbecile" was an official psychiatric and medical classification. It was used to identify adults who had the intellectual capacity or mental age of a young child (typically between three and seven years old, or an IQ roughly between 25 and 50). It was a middle tier of intellectual disability—ranking above an "idiot" but below a "moron".