Insanity is an ongoing state of extreme mental illness, which may cause abnormal or antisocial behaviors. If you bark at cats and meow at dogs, you might suffer from insanity.

The noun insanity originates from the Latin word insanitatem, meaning "unhealthfulness" relating to the mind. It is believed that master artist Vincent van Gogh, who cut off his ear and gave it to a prostitute, experienced periods of insanity. But this term can also refer to things people perceive as unconventional or foolish, like your neighbor who quit his job, sold all his belongings, and bought a boat to sail around the world.

Definitions of insanity

n relatively permanent disorder of the mind

saneness, sanity
normal or sound powers of mind
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insaneness, lunacy, madness
obsolete terms for legal insanity
dementedness, dementia
mental deterioration of organic or functional origin
irrationality, unreason
the state of being irrational; lacking powers of understanding
derangement, mental unsoundness, unbalance
a state of mental disturbance and disorientation
craziness, daftness, flakiness
informal terms for insanity
Korsakoff's psychosis, Korsakoff's syndrome, Korsakov's psychosis, Korsakov's syndrome, alcohol amnestic disorder, alcoholic dementia, polyneuritic psychosis
dementia observed during the last stages of severe chronic alcoholism; involves loss of memory for recent events although long term memory is intact
presenile dementia
dementia with onset before the age of 65
senile dementia, senile psychosis
dementia of the aged; results from degeneration of the brain in the absence of cerebrovascular disease
Type of:
mental disease, mental illness, psychopathy
any disease of the mind; the psychological state of someone who has emotional or behavioral problems serious enough to require psychiatric intervention

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