WordNet (r) 3.0 (2006):

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

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "nudist":
   bald, bare, bare-ass, bareness, birthday suit, decollete,
   ecdysiast, gymnosophical, gymnosophist, gymnosophy, in native buff,
   in puris naturalibus, in the altogether, in the buff, in the raw,
   naked, nakedness, naturism, naturist, naturistic, not a stitch,
   nude, nudism, nudity, peeled, raw, stark-naked, state of nature,
   stripper, stripteaser, the altogether, the nude, the raw,
   toplessness, with nothing on, without a stitch