lunatic lunatic /ˈluːnəˌtɪk/

adjective

1. () Insane and believed to be affected by the phases of the moon  ( moonstruck , lunatic )
   insane and believed to be affected by the phases of the moon
   

noun

1. A reckless impetuous irresponsible person  ( daredevil , harum-scarum , hothead , lunatic , madcap , swashbuckler )
   a reckless impetuous irresponsible person
   
   
2. An insane person  ( lunatic , headcase [Informal] , madman , maniac )
   an insane person
     The deranged madman rambled on the street, lost in his own delusions.
   The deranged madman rambled on the street, lost in his own delusions.