a raving or violently insane person; lunatic.

any intemperate or overly zealous or enthusiastic person

a maniac when it comes to details.

maniacal.

noun

bedlamite , bigot , crackpot * , enthusiast , fan , fanatic , fiend , flake * , freak , fruitcake , kook * , loon , loony * , lunatic , madperson , nut * , nutcase , psycho , psychopath , schizoid , screwball * , section 8 , zealotnotes:a maniac is an insane person , while manic means affected with or marked by frenzy or mania uncontrolled by reason , bug , devotee , zealot , crackpot , crazed , deranged , insane , madman , madwoman , nut

adjective

brainsick , crazy , daft , demented , disordered , distraught , dotty , lunatic , mad , maniacal , mentally ill , moonstruck , off , touched , unbalanced , unsound , wrong