The Collaborative International Dictionary of English v.0.48:

Nonconformist \Non`con*form"ist\, n.
   One who does not conform to an established church;
   especially, one who does not conform to the established
   church of England; a dissenter.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nonconformist
    adj 1: not conforming to some norm or socially approved pattern
           of behavior or thought; "their rabidly nonconformist
           deportment has made them legendary"; "the old stubborn
           nonconformist spirit of the early settlers" [syn:
           nonconformist, unconformist] [ant: conformist]
    2: not conforming to established customs or doctrines especially
       in religion [syn: nonconforming, nonconformist]
    n 1: a Protestant in England who is not a member of the Church
         of England [syn: Nonconformist, chapelgoer] [ant:
         Anglican]
    2: someone who refuses to conform to established standards of
       conduct [syn: nonconformist, recusant] [ant:
       conformist]