uncouth

From Middle English uncouth, from Old English uncūþ (“unknown; unfamiliar; strange”), from Proto-West Germanic *unkunþ, from Proto-Germanic *unkunþaz (“unknown”), equivalent to un- +‎ couth. The modern pronunciation does not show /aʊ/, the usual development of the Middle English vowel from the Great Vowel Shift. It is usually explained as a pronunciation taken from Northern English dialects, which did not undergo the diphthongization of the vowel.