circinus

circĭnus, i,

m.. = κίρκινος, a pair of compasses : flumen Dubis. ut circino circumductum, paene totum oppidum cingit, Caes. B. G. 1, 38: diducere, Vitr. 9, 7, 2: circino spatia dimetiri, id ib.; id. 10, 4, 1: ratio circini, Plin. 2, 15, 13, § 63.