Definition & Meaning of "mental midget"in English

What is the origin of the term "mental midget" and how is it used?

"Mental midget" is a slang insult that appeared in English in the 20th century, combining "mental" with "midget" to describe a person regarded as intellectually deficient or stupid. The metaphor likens a small stature to limited mental capacity, emphasizing perceived intellectual inadequacy. It is used in informal, often hostile or mocking contexts, such as conversation, media, or casual writing, to express contempt or ridicule. The term is clearly derogatory and intended to insult; it is never neutral.