The definition of a mental deficiency is something wrong or lacking in a person's brain, thought process or ability to think and learn.
Injuries to the nervous system
Severe intellectual disability. This term belongs to a classification system no longer in use.
(Music) A diminishing of tempo; a retard.
Find another word for mental-retardation. In this page you can discover 10 synonyms, antonyms, idiomatic expressions, and related words for mental-retardation, like: mental defect, mental deficiency, mental handicap, subnormality, dementia, brain-damage, backwardness, slowness, amentia and retardation.