<p><strong>Adjective:</strong></p><ul><li>of or relating to Neanderthal man.</li><li>(often lowercase) Informal. primitive, unenlightened, or reactionary; culturally or intellectually backward.</li></ul><p><strong>Noun:</strong></p><ul><li>Neanderthal man.</li><li>(often lowercase) Informal. an unenlightened or ignorant person; barbarian.</li><li>a reactionary; a person with very old-fashioned ideas.</li></ul>