law

Concise Oxford English Dictionary © 2008 Oxford University Press:
law/lɔː/

▶noun

• 1 a rule or system of rules recognized by a country or community as regulating the actions of its members and enforced by the imposition of penalties.

  ■ such rules as a subject of study or as the basis of the legal profession.

  ■ statute law and the common law.

  ■ something regarded as having binding force or effect: his word was law.

  ■ (the law) informal the police.

• 2 a rule defining correct procedure or behaviour in a sport.

• 3 a statement of fact, deduced from observation, to the effect that a particular natural or scientific phenomenon always occurs if certain conditions are present.

• 4 the body of divine commandments as expressed in the Bible or other religious texts.

  ■ (the Law) the Pentateuch.

  ■ (also the Law of Moses) the precepts of the Pentateuch.

– phrases
be a law unto oneself behave in an unconventional or unpredictable manner.
lay down the law issue instructions in an authoritative or dogmatic way.
take the law into one's own hands punish someone according to one's own ideas of justice, especially illegally or violently.

– origin OE lagu, from ON lag ‘something laid down or fixed’, of Gmc origin and rel. to lay1.