Source : Webster's Revised Unabridged Dictionary (1913)

Seaman \Sea"man\, n.; pl. {Seamen}.
   A merman; the male of the mermaid. [R.] ``Not to mention
   mermaids or seamen.'' --Locke.

Seaman \Sea"man\, n.; pl. {Seamen}. [AS. s[ae]man.]
   One whose occupation is to assist in the management of ships
   at sea; a mariner; a sailor; -- applied both to officers and
   common mariners, but especially to the latter. Opposed to
   {landman}, or {landsman}.

   {Able seaman}, a sailor who is practically conversant with
      all the duties of common seamanship.

   {ordinary seaman}. See {Ordinary}.

Source : WordNet®

seaman
     n 1: a man who serves as a sailor [syn: {mariner}, {tar}, {Jack-tar},
           {Jack}, {old salt}, {seafarer}, {gob}, {sea dog}]
     2: muckraking United States journalist who exposed bad
        conditions in mental institutions (1867-1922) [syn: {Elizabeth
        Seaman}, {Elizabeth Cochrane Seaman}, {Nellie Bly}]