Why is the ninth month called September?
"standard, pattern, model," 1821, from French norme, from Latin norma "carpenter's square, rule, pattern," of unknown origin. Klein suggests a borrowing (via Etruscan) of Greek gnomon "carpenter's square." The Latin form of the word, norma, was used in English in the sense of "carpenter's square" from 1670s.
rule or standard of behaviour shared by members of a social group. Norms may be internalized-i.e., incorporated within the individual so that there is conformity without external rewards or punishments, or they may be enforced by positive or negative sanctions from without. The social unit sharing particular norms may be small (e.g., a clique of friends) or may include all adult members of a society. Norms are more specific than values or ideals: honesty is a general value, but the rules defining what is honest behaviour in a particular situation are norms