An Etymological Dictionary of Astronomy and Astrophysics

General: A standard, model, or pattern regarded as typical.
Math.:

1. The magnitude of a vector expressed as the square root of the sum of the squares of the absolute values of the components of the vector.
   
2. The value that has the highest frequency within a statistical range.

Etymology (EN): From Fr. norme, from O.Fr., from L. norma “carpenter’s square, rule, pattern,” of unknown origin.

Etymology (PE): Hanjâr “a straight road; way, rule, law; habit, custom; conduct; a mason’s rule, a plumb-line, a level;” Mid.Pers. hanjâr “right, correct;” from Proto-Iranian *ham-cara-, *han-cara- prefixed *cara- “to move, walk” (cf. Av. car- “to move, go, walk,” carāni “I would go,” carāt “he would go;” Mod.Pers. caridan “to graze,” gozârdan “to explain,” gozâreš “explanation”); cf. Skt. samcara- “passage, way, road, path; going about, moving,” from prefix sam- + cara- “moving, going, walking;” Gk. pelomai “to move;” L. colere “to till, cultivate, inhabit.”