1) Doctrine 2) Naturism 3) Nudism 4) Philosophical system 5) Philosophy 6) School of thought 
deep contemplation performed while naked
• (n.) The doctrines of the Gymnosophists.
Gym·nos'o·phy (-fȳ) noun The doctrines of the Gymnosophists. Good. 
[n] - the doctrine of a sect of Hindu philosophers who practiced nudity and asceticism and meditation
gymnosophism, gymnosophy The supposed practices of Indian monks, as described by some confused early Chkristian writers. The term is Greek for 'naked sages'. Actually, only the ascetic Jains practiced Nudism, while Buddhists wore saffron robes.
noun the doctrine of a sect of Hindu philosophers who practiced nudity and asceticism and meditation