lunatic

(s) insane and believed to be affected by the phases of the moon moonstruck,

Nouns

(n) an insane person madman, maniac,
(n) a reckless impetuous irresponsible person daredevil, harum-scarum, madcap, swashbuckler, hothead,

Synonyms

madman maniac moonstruck daredevil harum-scarum madcap swashbuckler hothead

Words of close approximity

lunate

lunatic fringe