Emily Dickinson Lexicon

RULE, n. [W. rheol; Arm. reol; Sax. regol, reogol; Sw. Dan. G. and D. regel; Fr. regle; Sp. regla; Port. regoa, regra; It. regola; L. regula, from rego, to govern, that is, to stretch, strain or make straight. I suppose the Welsh rheol to be a contracted word.]

1. Government; sway; empire; control; supreme command or authority. A wise servant shall have rule over a son that causeth shame. Prov. xvii. And his stern rule the groaning land obey'd. Pope.
2. That which is established as a principle, standard or directory; that by which any thing is to be adjusted or regulated, or to which it is to be conformed; that which is settled by authority or custom for guidance and direction. Thus a statute or law is a rule of civil conduct; a canon is a rule of ecclesiastical government; the precept or command of a father, is a rule of action or obedience to children; precedents in law are rules of decision to judges; maxims and customs furnish rules for regulating our social opinions and manners. The laws of God are rules for directing us in life, paramount to all others. A rule which you do not apply, is no rule at all. J. M. Mason.
3. An instrument by which lines are drawn. A judicious artist will use his eye, but he will trust only to his rule. South.
4. Established mode or course of proceeding prescribed in private life. Every man should have some fixed rules for managing his own affairs.
5. In literature, a maxim, canon or precept to be observed in any art or science. Encyc.
6. In monasteries, corporations or societies, a law or regulation to be observed by the society and its particular members.
7. In courts, rules are the determinations and orders of court, to be observed by its officers in conducting the business of the court.
8. In arithmetic and algebra, a determinate mode prescribed for performing any operation and producing a certain result.
9. In grammar, an established form of construction in a particular class of words; or the expression of that form in words. Thus it is a rule in English, 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. Rule of three, is that rule of arithmetic 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.