norm (n.)

"a standard, pattern, or model," 1821 (Coleridge), from French norme, from Latin norma "carpenter's square, rule, pattern," a word of unknown origin. Klein suggests a borrowing (via Etruscan) of Greek gnōmōn "carpenter's square." The Latin form of the word, norma, was used in English in the sense of "carpenter's square" from 1670s, also as the name of a small, faint southern constellation introduced 18c. by La Caille.