[1] : The Collaborative International Dictionary of English v.0.48

mariner \mar"iner\, n. f. marinier, ll. marinarius. see
   marine.
   one whose occupation is to assist in navigating ships; a
   seaman or sailor. --chaucer.
   1913 webster

   mariner's compass. see under compass.
      1913 webster
see also:
marine mariner's compass compass 

[2] : WordNet (r) 2.0

mariner
     n : a man who serves as a sailor syn: seaman, tar, jack-tar,
          jack, old salt, seafarer, gob, sea dog
see also:
seaman tar jack-tar jack old salt seafarer 
gob sea dog 

[3] : Moby Thesaurus II by Grady Ward, 1.0

61 moby thesaurus words for "mariner":
   adventurer, alpinist, astronaut, bluejacket, camper, climber,
   comers and goers, commuter, cosmopolite, cruiser, excursionist,
   explorer, fare, globe-girdler, globe-trotter, gob, goer, hajji,
   jack, jack-tar, jet set, jet-setter, journeyer, limey, mountaineer,
   old salt, palmer, passenger, passerby, pathfinder, pilgrim,
   pioneer, rating, rubberneck, rubbernecker, sailor, salt, sea dog,
   seaman, shellback, sightseer, straphanger, swab, swabbie, tar,
   tarpaulin, tourer, tourist, trailblazer, trailbreaker, transient,
   traveler, trekker, tripper, viator, visiting fireman, voortrekker,
   voyager, voyageur, wayfarer, world-traveler

[4] : Bouvier's Law Dictionary, Revised 6th Ed (1856)

mariner. one whose occupation is to navigate vessels on the sea. vide seamen 
shipping articles. 
     2. by act of congress, 1 story, laws of u. s., ch. 56, s. 4, p. 109, it 
is provided, that no sum exceeding one dollar shall be recovered from any 
seaman or mariner in the merchant service, by any person, for any debt 
contracted during the time such seaman or mariner shall actually belong to 
any ship or vessel, until the voyage for which such seaman or mariner 
engaged, shall be ended. 

Mariner >> M Words
Mariner, definition of term: Mariner
mariner_pag1.html