n.

1. a principle or condition that customarily governs behavior;
   regulation
   
   • it was his rule to take a walk before breakfast
   • short haircuts were the regulation
2. something regarded as a normative example;
   convention, normal, pattern, formula
   
   • the convention of not naming the main character
   • violence is the rule not the exception
   • his formula for impressing visitors
3. prescribed guide for conduct or action;
   prescript
4. (linguistics) a rule describing (or prescribing) a linguistic practice;
   linguistic rule
5. a basic generalization that is accepted as true and that can be used as a basis for reasoning or conduct;
   principle
   
   • their principles of composition characterized all their works
6. a rule or law concerning a natural phenomenon or the function of a complex system;
   principle
   
   • the principle of the conservation of mass
   • the principle of jet propulsion
   • the right-hand rule for inductive fields
7. the duration of a monarch's or government's power
   
   • during the rule of Elizabeth
8. dominance or power through legal authority;
   dominion
   
   • France held undisputed dominion over vast areas of Africa
   • the rule of Caesar
9. directions that define the way a game or sport is to be conducted
   
   • he knew the rules of chess
10. any one of a systematic body of regulations defining the way of life of members of a religious order
    
    • the rule of St. Dominic
11. (mathematics) a standard procedure for solving a class of mathematical problems;
    formula
    
    • he determined the upper bound with Descartes' rule of signs
    • he gave us a general formula for attacking polynomials
12. measuring stick consisting of a strip of wood or metal or plastic with a straight edge that is used for drawing straight lines and measuring lengths;
    ruler

v.

1. exercise authority over; as of nations;
   govern
   
   • Who is governing the country now?
2. decide with authority;
   decree
   
   • The King decreed that all firstborn males should be killed
3. be larger in number, quantity, power, status or importance;
   predominate, dominate, reign, prevail
   
   • Money reigns supreme here
   • Hispanics predominate in this neighborhood
4. decide on and make a declaration about;
   find
   
   • find someone guilty
5. have an affinity with; of signs of the zodiac
6. mark or draw with a ruler
   
   • rule the margins
7. keep in check;
   harness, rein
   
   • rule one's temper