Lewis & Short

compulsor, ōris, m. [compello] (late Lat.).

  1. I. Lit., a driver (of cattle), Pall. Jun. 2, 3.
  2. II. Transf., one who asks or forces to a payment, an exacter of money, Amm. 22, 6, 1; Cod. Th. 8, 10, 3 and 4; 11, 7, 15.