—n. 1. a principle or regulation governing conduct, action, procedure, arrangement, etc.: the rules of chess. 2. the code of regulations observed by a religious order or congregation: the Franciscan rule. 3. the customary or normal circumstance, occurrence, manner, practice, quality, etc.: the rule rather than the exception. 4. control, government, or dominion: under the rule of a dictator. 5. tenure or conduct of reign or office: during the rule of George III. 6. a prescribed mathematical method for performing a calculation or solving a problem.
7. ruler (def. 2).
8. (cap.) Astron.the constellation Norma.
9. Print.a thin, type-high strip of metal, for printing a solid or decorative line or lines.
10. Law. a. a formal order or direction made by a court, as for governing the procedure of the court (general rule) or for sending the case before a referee (special rule). b. a legal principle.
c. a court order in a particular case.
a. a fixed area in the neighborhood of certain prisons within which certain prisoners were allowed to live.
b. the freedom of such an area.
13. as a rule, generally; usually: He arrives at eleven o'clock, as a rule.
—v.t. 1. to control or direct; exercise dominating power, authority, or influence over; govern: to rule the empire with severity. 2. to decide or declare judicially or authoritatively; decree: The judge ruled that he should be exiled. 3. to mark with lines, esp. parallel straight lines, with the aid of a ruler or the like: to rule paper. 4. to mark out or form (a line) by this method: to rule lines on paper. 5. to be superior or preeminent in (a specific field or group); dominate by superiority; hold sway over: For centuries, England ruled the seas.
—v.i. 1. to exercise dominating power or influence; predominate.
2. to exercise authority, dominion, or sovereignty.
3. to make a formal decision or ruling, as on a point at law.
4. to be prevalent or current: Higher prices ruled throughout France. 5. rule out, a. to prove to be unrelated or not for consideration; eliminate; exclude: to rule out the possibility of error. b. to make impossible or impracticable: The rainstorm ruled out the holiday camping. 6. rule the roost. See roost (def. 4).