WordNet sense 1 (relating to or belonging to or resembling Neanderthal man):

neandertal, Neanderthalian

WordNet sense 2 (extinct robust human of Middle Paleolithic in Europe and western Asia):

Neandertal man, Homo sapiens neanderthalensis, Neanderthal man

WordNet sense 3 (ill-mannered and coarse and contemptible in behavior or appearance):

boorish, loutish, oafish, swinish

WordNet sense 4 ((used of persons and their behavior) not refined; uncouth):

unrefined