Insanity

Part of speech: noun (n.)

1. The state of being insane; unsoundness or derangement of mind; madness; lunacy. All power of fancy overreason is a degree of insanity. Johnson. Without grace The heart's insanity admits no cure. Cowper.

2. Such a mental condition, as, either from the existence of delusions, or from incapacity to distinguish between right and wrong, with regard to any matter under action, does away with individual responsibility.