The Collaborative International Dictionary of English v.0.48:

Naturist \Na"tur*ist\, n.
   One who believes in, or conforms to, the theory of naturism.
   --Boyle.
   [1913 Webster]

WordNet (r) 3.0 (2006):

naturist
    n 1: a person who practices nudity for reasons of health or
         religion [syn: nudist, naturist]

Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "naturist":
   bareness, birthday suit, decollete, ecdysiast, gymnosophist,
   gymnosophy, nakedness, naturism, not a stitch, nudism, nudist,
   nudity, state of nature, stripper, stripteaser, the altogether,
   the nude, the raw, toplessness