The Collaborative International Dictionary of English v.0.48:

Courier \Cou"ri*er\ (k??"r?-?r), n. [F. courrier, fr. courre,
   courir, to run, L. currere. See Course, Current.]
   1. A messenger sent with haste to convey letters or
      dispatches, usually on public business.
      [1913 Webster]

            The wary Bassa . . . by speedy couriers, advertised
            Solyman of the enemy's purpose.       --Knolles.
      [1913 Webster]

   2. An attendant on travelers, whose business it is to make
      arrangements for their convenience at hotels and on the
      way.
      [1913 Webster]

Jargon File (4.4.4, 14 Aug 2003):

courier


   [BBS & cracker cultures] A person who distributes newly cracked
   warez, as opposed to a server who makes them available for
   download or a leech who merely downloads them. Hackers recognize
   this term but don't use it themselves, as the act is not part of
their
   culture. See also warez d00dz, cracker, elite.


Moby Thesaurus II by Grady Ward, 1.0:

48 Moby Thesaurus words for "courier":
   Gyropilot, Hermes, Iris, Mercury, Paul Revere, Pheidippides,
   automatic pilot, bearer, boatheader, boatsteerer, carrier,
   cicerone, commissionaire, cowherd, coxswain, diplomatic courier,
   dragoman, drover, emissary, envoy, estafette, express, go-between,
   goatherd, guide, guidepost, guider, helmsman, herd, herdsman,
   internuncio, mercury, message-bearer, messenger, navigator, nuncio,
   pilot, pointer, post, postboy, postrider, river pilot, runner,
   shepherd, steerer, steersman, tour director, tour guide