lawyoudaoicibaDictYouDict[law 词源字典]
law: [10] Etymologically, a law is that which has been ‘laid’ down. English borrowed the word from Old Norse *lagu (replacing the native Old English ǣ ‘law’), which was the plural of lag ‘laying, good order’. This came ultimately from the prehistoric Germanic base *lag- ‘put’, from which English gets lay. It has no etymological connection with the semantically similar legal.
=> lay[law etymology, law origin, 英语词源]
law (n.)youdaoicibaDictYouDict
Old English lagu (plural laga, comb. form lah-) "law, ordinance, rule, regulation; district governed by the same laws," from Old Norse *lagu "law," collective plural of lag "layer, measure, stroke," literally "something laid down or fixed," from Proto-Germanic *lagan "put, lay" (see lay (v.)).

Replaced Old English æ and gesetnes, which had the same sense development as law. Compare also statute, from Latin statuere; German Gesetz "law," from Old High German gisatzida; Lithuanian istatymas, from istatyti "set up, establish." In physics, from 1660s. Law and order have been coupled since 1796.