insanity

As nouns the difference between nightmare and insanity

is that nightmare is a female demon or monster, thought to plague people while they slept and cause a feeling of suffocation and terror during sleep while insanity is the state of being insane; madness.

As nouns the difference between abnormal and insanity

is that abnormal is a person or object that is not normal while insanity is the state of being insane; madness.

As an adjective abnormal

is not conforming to rule or system; deviating from the usual or normal type.

As nouns the difference between insanity and freak

is that insanity is the state of being insane; madness while freak is a man, particularly a bold, strong, vigorous man or freak can be a sudden causeless change or turn of the mind; a whim of fancy; a capricious prank; a vagary or caprice.

As a verb freak is

to make greatly distressed and/or a discomposed appearance.

As an adjective freak is

strange, weird.

As an adverb insanely

is in an insane manner.

As a noun insanity is

the state of being insane; madness.

As nouns the difference between insanity and illusion

is that insanity is the state of being insane; madness while illusion is anything that seems to be something that it is not.

Disorder is a related term of insanity.

As nouns the difference between disorder and insanity

is that disorder is absence of order; state of not being arranged in an orderly manner while insanity is the state of being insane; madness.

As nouns the difference between insanity and crazy

is that insanity is the state of being insane; madness while crazy is an insane or eccentric person; a crackpot.

As an adjective crazy is

insane; lunatic; demented.

As an adverb crazy is

(slang) very, extremely.

Hallucination is a related term of insanity.

As nouns the difference between hallucination and insanity

is that hallucination is a sensory perception of something that does not exist, often arising from disorder of the nervous system, as in delirium tremens; a delusion while insanity is the state of being insane; madness.

As nouns the difference between delusion and insanity

is that delusion is a false belief that is resistant to confrontation with actual facts while insanity is the state of being insane; madness.

Disturbance is a related term of insanity.

As nouns the difference between disturbance and insanity

is that disturbance is the act of disturbing, being disturbed while insanity is the state of being insane; madness.