Bylaw comes from Middle English bilawe, probably from Old Norse byr ('town, dwelling') + lagu ('law'), thus 'a town's own law', later reinterpreted as a 'secondary' (by-) law. The historical trail runs through byr in Old Norse and lagu in Old Norse. Morphologically, bylaw is transparent: it draws on Middle English bilawe, probably from Old Norse byr ('town, dwelling') + lagu ('law'), thus 'a town's own law', later reinterpreted as a 'secondary' (by-) law. Used as a noun, bylaw now means "a rule made by an organization or local authority to regulate its affairs", so the present definition can be read against the older forms and meanings. The same lexical family is also visible in related forms such as by and law. The result is a borrowed or transmitted form whose modern spelling carries a compact record of its route into English.