also by-law, late 13c., bilage "local ordinance," from Old Norse or Old Danish bi-lagu "town law," from byr "place where people dwell, town, village," from bua "to dwell" (from PIE root *bheue- "to be, exist, grow") + lagu "law" (see law). So, a local law pertaining to local residents, hence "a standing rule of a corporation or association for regulation of its organization and conduct." Sense influenced by by.