norm

1 :  an authoritative standard :  model

2 :  a principle of right action binding upon the members of a group and serving to guide, control, or regulate proper and acceptable behavior No society lacks norms governing conduct. — Robert K. Merton

3 :  average: such asa :  a set standard of development or achievement usually derived from the average or median achievement of a large groupb :  a pattern or trait taken to be typical in the behavior of a social group studies aimed at establishing the norms of sexual behavior among the middle classesc :  a widespread or usual practice, procedure, or custom standing ovations became the norm Bilingualism is the norm in many countries.

4a :  a real-valued nonnegative function defined on a vector space with value analogous to length and satisfying the conditions that the function is zero if and only if the vector (see ¹vector 1a) is zero, the function of the product of a scalar and a vector is equal to the product of the absolute value of the scalar and the function of the vector, and the function of the sum of two vectors is less than or equal to the sum of the functions of the two vectors; specifically :  the square root of the sum of the squares of the absolute values of the elements of a matrix (see matrix 5a) or of the components of a vectorb :  the greatest distance between two successive points of a set of points that partition an interval (see interval 2a) into smaller intervals