WordWeb Online

1. An insane person
   - lunatic, madman, crazy [N. Amer, informal], loony [informal], looney [informal], nutcase [informal], headcase [informal]
    
2. A person who has an obsession with or excessive enthusiasm for something

1. Wildly disordered
   "a maniac frenzy";
   - maniacal

Derived forms: maniacs

See also: basket case [informal], fruitcake [informal], insane, mentalist [Brit, informal], nutbar [N. Amer, informal], nutcake [US, informal], nutjob [informal], nutter [Brit, informal], wackadoodle [N. Amer, informal], wackjob [N. Amer, informal], wacko [informal], whackjob [N. Amer, informal], whacko [informal]

Type of: diseased person, enthusiast, fancier, sick person, sufferer

Encyclopedia: Maniac