5. (noun)convention, normal, pattern, rule, formula something regarded as a normative example "the convention of not naming the main character"; "violence is the rule not the exception"; "his formula for impressing visitors"
7. (noun)rule, formula (mathematics) a standardprocedure for solving a class of mathematical problems "he determined the upper bound with Descartes' rule of signs"; "he gave us a general formula for attacking polynomials"