Lewis & Short

2. portĭtor, ōris, m. [from the root por, whence porto, a bearer, carrier].

  1. I. A carrier, conveyer.
    1. A. Usually one who conveys people in a boat or ship.
      1. 1. In gen., a ferryman, boatman, sailor, mariner (poet. and in post-Aug. prose): Plato cum flumen nave transisset, non ab illo quicquam portitor exegisset, etc., Sen. Ben. 6, 18, 1.
      2. 2. In partic., the ferryman, i. e. Charon (poet.): ubi portitor aera recepit, etc., Prop. 4 (5), 11, 7: Orci, Verg. G. 4, 502; id. A. 6, 298: Lethaei amnis, Stat. Th. 12, 559; Val. Fl. 1, 784 et saep.
    2. B. By land, a carrier, carter, wagoner: Portitor Ursae, i. e. the constellation Bootes, who, as it were, drives the wain, Stat. Th. 1, 693.
  2. II. A bearer, carrier (mostly post-class.; cf. bajulus): Helles, i. e. the Ram, Col. 10, 155 (in Mart. 9, 72, 7, we read proditor Helles): lecti sui, Claud. Epigr. 49, 17: frumenti, Cod. Just. 11, 4, 1: ciborum, Prud. στεφ. 5, 405: apicum, Sid. Ep. 6, 3.