- The term "lunatic" derives from the Latin word lunaticus, which originally referred mainly to epilepsy and madness, as diseases thought to be caused by the moon.
- Insanity.
- Intermittent insanity, formerly believed tobe related to phases of the moon.
- Extreme foolishness or an instance of it.
-Unsoundness of mind sufficient to incapacitate one for civil transactions: a former legal term.