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. Cf. 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.
A rule of conduct or procedure established by custom, agreement, or authority.
A set of rules or principles for a specific area of a legal system.
A piece of enacted legislation.
A formulation describing a relationship observed to be invariable between or among phenomena for all cases in which the specified conditions are met.
A generalization based on consistent experience or results.
A statement that describes invariable relationships among phenomena under a specified set of conditions. Boyle's law, for instance, describes what will happen to the volume of an ideal gas if its pressure changes and its temperature remains the same. The conditions under which some physical laws hold are idealized (for example, there are no ideal gases in the real world), thus some physical laws apply universally but only approximately. See Note at hypothesis.