moron

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A stupid person; a dolt.
2. n. Psychology A person of mild mental retardation having a mental age of from 7 to 12 years and generally having communication and social skills enabling some degree of academic or vocational education. The term belongs to a classification system no longer in use and is now considered offensive.

Century Dictionary and Cyclopedia

1. n. A variety of salamander.

Wiktionary

1. n. obsolete A person of borderline intelligence in the former classification of mental retardation, having of an intelligence quotient of 50-69.
2. n. informal A person who makes uncool, unfunny, uninteresting, or irrelevant (see lame) attempts to impress others and draw attention to himself, especially in a flawed attempt to act like someone else.
3. n. slang An idiot.

GNU Webster's 1913

1. n. (Pedagogy) A mentally retarded person whose intellectual development proceeds normally up to about the eighth year of age and is then arrested so that there is little or no further development; an adult having the mental development of an 8-to-12-year old. A moron is considered capable of doing routine work under supervision.
2. n. informal, derogatory Hence, a very stupid person.
3. n. An inferior olive size having a woody pulp and a large clingstone pit, growing in the mountainous and high-valley districts around the city of Moron, in Spain.

WordNet 3.0

1. n. a city in Argentina, to the west of Buenos Aires
2. n. a person of subnormal intelligence