.
I do agree with you, KimvdLinde, on ClothesFree being unacceptable.  Worse than being commercial, to me, is that it is a fad.  It's also saying what the movement is AGAINST instead of what it's FOR. It's also a euphemism for people too prudish to say out loud NUDE or NUDITY.
But then naturism and FKK are euphemisms, too, which encylopedias should avoid.  That's why, even though culturally I fit in more with "naturists", I prefer the word nudist.  But I don't want to try to force the heading "Nudism", by itself, on an unwilling group of Wikipedians.
The near perfect solution is the heading Social nudity or Nudity, social, isn't it?  Not a euphemism.  Even though it's not part of everyday speech, everyone instantly understands it, even quicker than they understand "Citrus fruit".  My second choice would be Nudism, naturism, public nudity, and related practices, but that's a bit awkward.