Rule of thumb

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. [1913 Webster]

We profess to have embraced a religion which contains the most exact rules for the government of our lives. --Tillotson. [1913 Webster]

2. Hence: (a) Uniform or established course of things. [1913 Webster]

'T is against the rule of nature. --Shak. [1913 Webster] (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.] [1913 Webster]

This uncivil rule; she shall know of it. --Shak. [1913 Webster]

3. The act of ruling; administration of law; government; empire; authority; control. [1913 Webster]

Obey them that have the rule over you. --Heb. xiii. 17. [1913 Webster]

His stern rule the groaning land obeyed. --Pope. [1913 Webster]

4. (Law) An order regulating the practice of the courts, or an order made between parties to an action or a suit. --Wharton. [1913 Webster]

5. (Math.) A determinate method prescribed for performing any operation and producing a certain result; as, a rule for extracting the cube root. [1913 Webster]

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. [1913 Webster]

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. [1913 Webster]

A judicious artist will use his eye, but he will trust only to his rule. --South. [1913 Webster]

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}. [1913 Webster]

{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 the road} (Law), any of the various regulations imposed upon travelers by land or water for their mutual convenience or safety. In the United States it is a rule of the road that land travelers passing in opposite directions shall turn out each to his own right, and generally that overtaking persons or vehicles shall turn out to the left; in England the rule for vehicles (but not for pedestrians) is the opposite of this.

{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. [1913 Webster]