WordNet (r) 3.0 (2006):

caveman
    n 1: someone who lives in a cave [syn: caveman, cave man,
         cave dweller, troglodyte]

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "caveman":
   Bronze Age man, Hominidae, Iron Age man, Stone Age man, aboriginal,
   aborigine, ancient, antediluvian, anthropoid, ape-man, autochthon,
   bucko, bushman, cave dweller, fossil man, he-man, hominid,
   humanoid, jock, jockstrap, man of old, missing link, preadamite,
   prehistoric man, prehuman, primate, primitive, protohuman,
   troglodyte