- Usually Offensive. a developmental disorder characterized in varying degrees by a subnormal ability to learn, a substantially low IQ, and impaired social adjustment.
- psychiatry the condition of having a low intelligence quotient (below 70)
- Subnormal intellectual development or functioning that is the result of congenital causes, brain injury, or disease and is characterized by any of various deficiencies, ranging from impaired learning ability to social and vocational inadequacy.mental deficiency
- Below-average intellectual ability resulting from a genetic defect, brain injury, or disease, and usually present from birth or early infancy.