Source : Webster's Revised Unabridged Dictionary (1913)

Rule \Rule\, n. [OE. reule, riule, OF. riule, reule, F.
   r['e]gle, fr. L. regula a ruler, rule, model, fr. regere,
   rectum, to lead straight, to direct. See {Right}, a., and cf.
   {Regular}.]
   1. That which is prescribed or laid down as a guide for
      conduct or action; a governing direction for a specific
      purpose; an authoritative enactment; a regulation; a
      prescription; a precept; as, the rules of various
      societies; the rules governing a school; a rule of
      etiquette or propriety; the rules of cricket.

            We profess to have embraced a religion which
            contains the most exact rules for the government of
            our lives.                            --Tillotson.

   2. Hence:
      (a) Uniform or established course of things.

                'T is against the rule of nature. --Shak.
      (b) Systematic method or practice; as, my ule is to rise
          at six o'clock.
      (c) Ordibary course of procedure; usual way; comon state
          or condition of things; as, it is a rule to which
          there are many exeptions.
      (d) Conduct in general; behavior. [Obs.]

                This uncivil rule; she shall know of it. --Shak.

   3. The act of ruling; administration of law; government;
      empire; authority; control.

            Obey them that have the rule over you. --Heb. xiii.
                                                  17.

            His stern rule the groaning land obeyed. --Pope.

   4. (Law) An order regulating the practice of the courts, or
      an order made between parties to an action or a suit.
      --Wharton.

   5. (Math.) A determinate method prescribed for performing any
      operation and producing a certain result; as, a rule for
      extracting the cube root.

   6. (Gram.) A general principle concerning the formation or
      use of words, or a concise statement thereof; thus, it is
      a rule in England, that s or es, added to a noun in the
      singular number, forms the plural of that noun; but
      ``man'' forms its plural ``men'', and is an exception to
      the rule.

   7.
      (a) A straight strip of wood, metal, or the like, which
          serves as a guide in drawing a straight line; a ruler.
      (b) A measuring instrument consisting of a graduated bar
          of wood, ivory, metal, or the like, which is usually
          marked so as to show inches and fractions of an inch,
          and jointed so that it may be folded compactly.

                A judicious artist will use his eye, but he will
                trust only to his rule.           --South.

   8. (Print.)
      (a) A thin plate of metal (usually brass) of the same
          height as the type, and used for printing lines, as
          between columns on the same page, or in tabular work.
      (b) A composing rule. See under {Conposing}.

   {As a rule}, as a general thing; in the main; usually; as, he
      behaves well, as a rule.

   {Board rule}, {Caliber rule}, etc. See under {Board},
      {Caliber}, etc.

   {Rule joint}, a knuckle joint having shoulders that abut when
      the connected pieces come in line with each other, and
      thus permit folding in one direction only.

   {Rule of three} (Arith.), that rule which directs, when three
      terms are given, how to find a fourth, which shall have
      the same ratio to the third term as the second has to the
      first; proportion. See {Proportion}, 5
      (b) .

   {Rule of thumb}, any rude process or operation, like that of
      using the thumb as a rule in measuring; hence, judgment
      and practical experience as distinguished from scientific
      knowledge.

   Syn: regulation; law; precept; maxim; guide; canon; order;
        method; direction; control; government; sway; empire.