/in san"i tee/ , n. , pl. insanities .
1. the condition of being insane; a derangement of the mind.
2. Law. such unsoundness of mind as affects legal responsibility or capacity.
3. Psychiatry. (formerly) psychosis.
4. extreme folly; senselessness; foolhardiness.
[ 1580-90; insanitas. See IN- 3 , SANITY ]
Syn. 1. dementia, lunacy, madness, craziness, mania, aberration.