The Collaborative International Dictionary of English v.0.48:

Oarsman \Oars"man\ ([=o]rz"man), n.; pl. Oarsmen (-men).
   One who uses, or is skilled in the use of, an oar; a rower.
   [1913 Webster]

         At the prow of the boat, rose one of the oarsmen.
                                                  --Longfellow.
   [1913 Webster]

WordNet (r) 3.0 (2006):

oarsman
    n 1: someone who rows a boat [syn: oarsman, rower]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "oarsman":
   bargee, bargeman, barger, boat-handler, boater, boatman, boatsman,
   ferrier, ferryman, galley slave, gondolier, lighterman, oar,
   punter, rower, waterman, yachter, yachtsman