Mercēdŏnĭus

or Mercēdī-nus, = Μερκηδόνιος, Μερκεδῖνος, mensis, an intercalary month of 22 or 23 days, inserted every two years in the calendar of Numa, Vet. Kalend. Rom. ap. Grut. 133; cf. so Laur. Lyd. de Mens. 4, 92.