I.a square, employed by carpenters, masons, etc., for making right angles (cf. regula).
II. Trop., a rule, pattern, precept: “nec sunt haec rhythmicorum aut musicorum acerrima norma dirigenda,” Cic. de Or. 3, 49, 190: “vitam ad certam rationis normam dirigere,” id. Mur. 2, 3: “numquam ego dicam Fabricium, Curtium, Coruncanium ad istorum (Stoicorum) normam fuisse sapientes,” id. Lael. 5, 18: “hanc normam, hanc regulam, hanc praescriptionem esse naturae,” id. Ac. 2, 46, 140: “natura norma legis est,” id. Leg. 2, 24, 61: “juris,” id. de Or. 2, 42, 178: “loquendi,” Hor. A. P. 72: “norma et regula oratoris,” Plin. Ep. 9, 26, 8.