From Middle High German nāchbūre, syncopic form of nāchgebūre, from Old High German nāhgibūro, from Proto-Germanic *nēhwagabūrô. Cognate with German Nachbar, Dutch nabuur, English neighbour. The devoicing of the labial was likely caused by the preceding voiceless -ch- in Middle High German. Alternatively it may be simply because postvocalic -b- is very rare in Luxembourgish.