The Collaborative International Dictionary of English v.0.48:

Coxswain \Cox"swain`\ (k?k"sw?n, Colloq. k?k"s'n), n.
   See Cockswain.
   [1913 Webster]

WordNet (r) 3.0 (2006):

coxswain
    n 1: the helmsman of a ship's boat or a racing crew [syn:
         coxswain, cox]

Moby Thesaurus II by Grady Ward, 1.0:

31 Moby Thesaurus words for "coxswain":
   Gyropilot, automatic pilot, boatheader, boatsteerer, cicerone,
   conner, courier, cowherd, cox, docking pilot, dragoman, drover,
   goatherd, guide, guidepost, guider, helmsman, herd, herdsman,
   mercury, navigator, pilot, pointer, river pilot, sailing master,
   shepherd, steerer, steersman, tour director, tour guide,
   wheelman