rēgula ae, f
REG-, a straight stick, bar, staff : quadratas regulas defigunt, Cs.— A ruler, rule : egere regulis.—Fig., a rule, pattern, model, example, principle : naturae: regula, quā vera et falsa iudicarentur: philosophiae: adsit Regula, peccatis quae poenas inroget aequas, H.