byelawyoudaoicibaDictYouDict[byelaw 词源字典]
byelaw: [13] Although nowadays often subconsciously thought of as being a ‘secondary or additional law’, in fact byelaw has no connection with by. The closest English relatives of its first syllable are be, boor, bower, both, bound ‘about to go’, build, burly, byre, and the second syllable of neighbour. It comes ultimately from the Germanic base *bu- ‘dwell’, and is assumed to have reached English via an unrecorded Old Norse *býlagu ‘town law’, a compound of býr ‘place where people dwell, town, village’, and lagu, source of English law.

It thus originally meant ‘law or regulation which applied only to a particular local community’, rather than the whole country.
=> be, boor, booth, bower, build, burly, byre, neighbour[byelaw etymology, byelaw origin, 英语词源]