Source : Webster's Revised Unabridged Dictionary (1913)

Captain \Cap"tain\, v. t.
   To act as captain of; to lead. [R.]

         Men who captained or accompanied the exodus from
         existing forms. --Lowell.

Captain \Cap"tain\, a.
   Chief; superior. [R.]

         captain jewes in the carcanet.           --Shak.

Captain \Cap"tain\ (k[a^]p"t[i^]n), n. [OE. capitain, captain,
   OF. capitain, F. capitaine (cf. Sp. capitan, It. capitano),
   LL. capitaneus, capitanus, fr. L. caput the head. See under
   {Chief}, and cf. {Chieftain}.]
   1. A head, or chief officer; as:
      (a) The military officer who commands a company, troop, or
          battery, or who has the rank entitling him to do so
          though he may be employed on other service.
      (b) An officer in the United States navy, next above a
          commander and below a commodore, and ranking with a
          colonel in the army.
      (c) By courtesy, an officer actually commanding a vessel,
          although not having the rank of captain.
      (d) The master or commanding officer of a merchant vessel.
      (e) One in charge of a portion of a ship's company; as, a
          captain of a top, captain of a gun, etc.
      (f) The foreman of a body of workmen.
      (g) A person having authority over others acting in
          concert; as, the captain of a boat's crew; the captain
          of a football team.

                A trainband captain eke was he.   --Cowper.

                The Rhodian captain, relying on . . . the
                lightness of his vessel, passed, in open day,
                through all the guards.           --Arbuthnot.

   2. A military leader; a warrior.

            Foremost captain of his time.         --Tennyson.

   {Captain general}.
      (a) The commander in chief of an army or armies, or of the
          militia.
      (b) The Spanish governor of Cuba and its dependent
          islands.

   {Captain lieutenant}, a lieutenant with the rank and duties
      of captain but with a lieutenant's pay, -- as in the first
      company of an English regiment.

Source : WordNet®

captain
     n 1: an officer holding a rank below a major but above a
          lieutenant
     2: the naval officer in command of a military ship [syn: {skipper}]
     3: a policeman in charge of a precinct [syn: {police captain},
        {police chief}]
     4: an officer who is licensed to command a merchant ship [syn:
        {master}, {sea captain}, {skipper}]
     5: the leader of a group of people; "a captain of industry"
        [syn: {chieftain}]
     6: the pilot ins charge of an airship [syn: {senior pilot}]
     7: a diningroom attendant who is in charge of the waiters and
        the seating of customers [syn: {headwaiter}, {maitre
        d'hotel}, {maitre d'}]

captain
     v : be the captain of a sports team