rules

a principle or condition that customarily governs behavior;
something regarded as a normative example;
prescribed guide for conduct or action
(linguistics) a rule describing (or prescribing) a linguistic practice
a basic generalization that is accepted as true and that can be used as a basis for reasoning or conduct;
the duration of a monarch's or government's power;
dominance or power through legal authority;
directions that define the way a game or sport is to be conducted;

any one of a systematic body of regulations defining the way of life of members of a religious order;
a rule or law concerning a natural phenomenon or the function of a complex system;
(mathematics) a standard procedure for solving a class of mathematical problems;
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
exercise authority over; as of nations;
decide with authority;
be larger in number, quantity, power, status or importance;
decide on and make a declaration about;
have an affinity with; of signs of the zodiac
mark or draw with a ruler;
keep in check;

rules is a valid Scrabble (US) TWL word

rules is a valid Scrabble Word in Merriam-Webster MW Dictionary

rules is a valid Scrabble Word in International Collins CSW Dictionary

rules is a valid Words With Friends word