Mental-deficiency meaning

They had a mental deficiency of which they were unconscious, and, naturally enough, supposed that those who affirmed they were possessed of it were romancing."

The Cyclops is totally mindless and instinctive, the lowest depths of mental deficiency capable of post-natal existence.

When mental deficiency and the attendant diseases or disorders are severe, the child may require a life-support system.

When the mental deficiency is less severe, the child may be diagnosed with minimal brain dysfunction or as neurologically handicapped.