sea rover

from WordNet (r) 3.0 (2006)

sea rover
    n 1: someone who robs at sea or plunders the land from the sea
         without having a commission from any sovereign nation [syn:
         {pirate}, {buccaneer}, {sea robber}, {sea rover}]

from The Collaborative International Dictionary of English v.0.48

Sea rover \Sea" rov"er\
   One that cruises or roves the sea for plunder; a sea robber;
   a pirate; also, a piratical vessel.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

56 Moby Thesaurus words for "sea rover":
      AB, Ancient Mariner, Argonaut, Blackbeard, Captain Hook,
      Captain Kidd, Dylan, Flying Dutchman, Henry Morgan, Jean Lafitte,
      Neptune, OD, Poseidon, Varuna, able seaman, able-bodied seaman,
      air pirate, airplane hijacker, bluejacket, buccaneer, corsair,
      deep-sea man, fair-weather sailor, fisherman, freebooter, hearty,
      jack, jack afloat, jack-tar, jacky, limey, lobsterman, mariner,
      matelot, navigator, picaroon, pirate, privateer, rover, sailor,
      salt, sea dog, sea king, sea robber, sea wolf, seafarer,
      seafaring man, seaman, shipman, skyjacker, tar, viking, water dog,
      whaler, windjammer, windsailor