neandertal vs neanderthal

neandertal and neanderthal both are adjectives.

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

As adjectives, neandertal and neanderthal are synonyms defined as:

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

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

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