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2.
a person who exhibits actions that could be a potential danger to him/herself or others.
The murderer was criminally insane.
by JIMMYJAMS! November 29, 2011
 
1.
A mental defect or disease that makes it impossible for a person to understand the wrongfulness of his acts or, even if he understands them, to ditinguish right from wrong.

If anyone is charge with a crime and is found to be criminally insane they cannot be convicted of the crime.
The character Jack Torrance from the Shining was criminally insane.
by Penny Acton September 13, 2006