The Collaborative International Dictionary of English v.0.48:

Master \Mas"ter\ (m[.a]s"t[~e]r), n. [OE. maistre, maister, OF.
   maistre, mestre, F. ma[^i]tre, fr. L. magister, orig. a
   double comparative from the root of magnus great, akin to Gr.
   me`gas. Cf. Maestro, Magister, Magistrate, Magnitude,
   Major, Mister, Mistress, Mickle.]
   1. A male person having another living being so far subject
      to his will, that he can, in the main, control his or its
      actions; -- formerly used with much more extensive
      application than now.
      (a) The employer of a servant.
      (b) The owner of a slave.
      (c) The person to whom an apprentice is articled.
      (d) A sovereign, prince, or feudal noble; a chief, or one
          exercising similar authority.
      (e) The head of a household.
      (f) The male head of a school or college.
      (g) A male teacher.
      (h) The director of a number of persons performing a
          ceremony or sharing a feast.
      (i) The owner of a docile brute, -- especially a dog or
          horse.
      (j) The controller of a familiar spirit or other
          supernatural being.
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   2. One who uses, or controls at will, anything inanimate; as,
      to be master of one's time. --Shak.
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            Master of a hundred thousand drachms. --Addison.
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            We are masters of the sea.            --Jowett
                                                  (Thucyd.).
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   3. One who has attained great skill in the use or application
      of anything; as, a master of oratorical art.
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            Great masters of ridicule.            --Macaulay.
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            No care is taken to improve young men in their own
            language, that they may thoroughly understand and be
            masters of it.                        --Locke.
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   4. A title given by courtesy, now commonly pronounced
      m[i^]ster, except when given to boys; -- sometimes written
      Mister, but usually abbreviated to Mr.
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   5. A young gentleman; a lad, or small boy.
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            Where there are little masters and misses in a
            house, they are impediments to the diversions of the
            servants.                             --Swift.
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   6. (Naut.) The commander of a merchant vessel; -- usually
      called captain. Also, a commissioned officer in the navy
      ranking next above ensign and below lieutenant; formerly,
      an officer on a man-of-war who had immediate charge, under
      the commander, of sailing the vessel.
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   7. A person holding an office of authority among the
      Freemasons, esp. the presiding officer; also, a person
      holding a similar office in other civic societies.
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   Little masters, certain German engravers of the 16th
      century, so called from the extreme smallness of their
      prints.

   Master in chancery, an officer of courts of equity, who
      acts as an assistant to the chancellor or judge, by
      inquiring into various matters referred to him, and
      reporting thereon to the court.

   Master of arts, one who takes the second degree at a
      university; also, the degree or title itself, indicated by
      the abbreviation M. A., or A. M.

   Master of the horse, the third great officer in the British
      court, having the management of the royal stables, etc. In
      ceremonial cavalcades he rides next to the sovereign.

   Master of the rolls, in England, an officer who has charge
      of the rolls and patents that pass the great seal, and of
      the records of the chancery, and acts as assistant judge
      of the court. --Bouvier. --Wharton.

   Past master,
      (a) one who has held the office of master in a lodge of
          Freemasons or in a society similarly organized.
      (b) a person who is unusually expert, skilled, or
          experienced in some art, technique, or profession; --
          usually used with at or of.

   The old masters, distinguished painters who preceded modern
      painters; especially, the celebrated painters of the 16th
      and 17th centuries.

   To be master of one's self, to have entire self-control;
      not to be governed by passion.

   To be one's own master, to be at liberty to act as one
      chooses without dictation from anybody.
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   Note: Master, signifying chief, principal, masterly,
         superior, thoroughly skilled, etc., is often used
         adjectively or in compounds; as, master builder or
         master-builder, master chord or master-chord, master
         mason or master-mason, master workman or
         master-workman, master mechanic, master mind, master
         spirit, master passion, etc.
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               Throughout the city by the master gate.
                                                  --Chaucer.
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   Master joint (Geol.), a quarryman's term for the more
      prominent and extended joints traversing a rock mass.

   Master key, a key adapted to open several locks differing
      somewhat from each other; figuratively, a rule or
      principle of general application in solving difficulties.


   Master lode (Mining), the principal vein of ore.

   Master mariner, an experienced and skilled seaman who is
      certified to be competent to command a merchant vessel.

   Master sinew (Far.), a large sinew that surrounds the hough
      of a horse, and divides it from the bone by a hollow
      place, where the windgalls are usually seated.

   Master singer. See Mastersinger.

   Master stroke, a capital performance; a masterly
      achievement; a consummate action; as, a master stroke of
      policy.

   Master tap (Mech.), a tap for forming the thread in a screw
      cutting die.

   Master touch.
      (a) The touch or skill of a master. --Pope.
      (b) Some part of a performance which exhibits very
          skillful work or treatment. "Some master touches of
          this admirable piece." --Tatler.

   Master work, the most important work accomplished by a
      skilled person, as in architecture, literature, etc.;
      also, a work which shows the skill of a master; a
      masterpiece.

   Master workman, a man specially skilled in any art,
      handicraft, or trade, or who is an overseer, foreman, or
      employer.
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The Collaborative International Dictionary of English v.0.48:

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.
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                A trainband captain eke was he.   --Cowper.
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                The Rhodian captain, relying on . . . the
                lightness of his vessel, passed, in open day,
                through all the guards.           --Arbuthnot.
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   2. A military leader; a warrior.
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            Foremost captain of his time.         --Tennyson.
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   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.
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The Collaborative International Dictionary of English v.0.48:

Captain \Cap"tain\, v. t.
   To act as captain of; to lead. [R.]
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         Men who captained or accompanied the exodus from
         existing forms. --Lowell.
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The Collaborative International Dictionary of English v.0.48:

Captain \Cap"tain\, a.
   Chief; superior. [R.]
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         captain jewes in the carcanet.           --Shak.
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WordNet (r) 3.0 (2006):

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:
       captain, skipper]
    3: a policeman in charge of a precinct [syn: captain, police
       captain, police chief]
    4: an officer who is licensed to command a merchant ship [syn:
       master, captain, sea captain, skipper]
    5: the leader of a group of people; "a captain of industry"
       [syn: captain, chieftain]
    6: the pilot in charge of an airship [syn: captain, senior
       pilot]
    7: a dining-room attendant who is in charge of the waiters and
       the seating of customers [syn: captain, headwaiter,
       maitre d'hotel, maitre d']
    v 1: be the captain of a sports team