Moron is a term once used in psychology to denote mild mental retardation. The term was closely tied with the American eugenics movement. Once the term became popularized, it fell out of use by the psychological community, as it was used more commonly as an insult than as a psychological term. Origin and uses
"Moron" was coined in 1910 by psychologist Henry H. Goddard from the Ancient Greek word μωρός (moros), which meant "dull" (as opposed to oxy, which meant "sharp"), and used to describe a person with a mental age in adulthood of between 8 and 12 on the Binet scale. It was once applied to people with an IQ of 51-70, being superior in one degree to "imbecile" (IQ of 26-50) and superior in two degrees to "idiot" (IQ of 0-25). The word moron, along with others including, "idiotic," "imbecilic," "stupid," and "feeble-minded," was formerly considered a valid descriptor in the psychological community, but it is now deprecated in use by psychologists.
Following opposition to Goddard's attempts to popularize his ideas, Goddard recanted his earlier claims about the moron: "It may still be objected that moron parents are likely to have imbecile or idiot children. There is not much evidence that this is the case. The danger is probably negligible."