In a state of mind which prevents normal perception, behaviour, or social interaction; seriously mentally ill
she was examined by three doctors and declared insane
General paralysis of the insane, a condition associated with the late stages of syphilis which is characterized by a combination of dementia, weakness of the limbs, speech and hearing difficulties, and various other symptoms
(In early use) paralysis involving the whole body; (later) specifically (more fully general paralysis of the insane) a late manifestation of syphilis in which there is inflammation and atrophy of brain tissue, especially of the frontal and temporal lobes, resulting in a variety of psychiatric and neurological symptoms such as dementia, psychosis, seizures, and generalized muscle weakness; = paresis. Abbreviated GPI.