This is a commonly used term but one that actually has a very specific meaning. Technically a person with mental retardation scores below 70 on an intelligence test and, as such has limited mental abilities. As we have become much more politically correct, this term is used less frequently and has been somewhat replaced by the term "mentally challenged". However, mental retardation is still the clinical term for someone who scores lower than 70 on intelligence tests, has limited mental capabilities, and difficulty dealing with day-day-day aspects of living. There is a range of mental retardation from mild to profound.