you affected by lunacy; an insane person, esp. one who features lucid periods; a madman; you of unsound head.
one impacted with lunacy; particularly, an insane individual who features lucid periods, or one whoever unsoundness of thoughts are acquired, perhaps not congenital, as distinguished from an idiot.
More generally speaking (as well as in law), any person of unsound mind. See more under lunacy and insanity.
How would you define lunatic?