neanderthal vs neandertal

neanderthal and neandertal both are adjectives.

Word	Noun	Adjective	Verb	Adverb
neanderthal	No	Yes	No	No
neandertal	No	Yes	No	No

As adjectives, neanderthal and neandertal are synonyms defined as:

neanderthal and neandertal: ill-mannered and coarse and contemptible in behavior or appearance

Other synonyms of neanderthal include boorish, loutish, oafish, swinish.

neanderthal (adjective)	neandertal (adjective)
ill-mannered and coarse and contemptible in behavior or appearance	ill-mannered and coarse and contemptible in behavior or appearance