Lewis & Short

‡ 1. mercēdŏnĭus, a, um, adj. [1. merces-do],

  1. I. of or belonging to the payment of wages: Mercedonios (dies) dixerunt a mercede solvendā, on which wages are paid, pay-days, Paul. ex Fest. p. 124 Müll.
  2. II. Subst.: mercēdŏnĭus, ii, m., a payer of wages, paymaster: mercedonius, qui solvit mercedem; ‡ mercedarius (an employer), qui dat mercedem pro labore sibi impenso, Gloss. Isid. 37.
    3. ‡†
      1. 2. 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.