The Collaborative International Dictionary of English v.0.48:

Half-deck \Half"-deck`\ (-d[e^]k`), n.
   1. (Zool.) A shell of the genus Crepidula; a boat shell.
      See Boat shell.
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   2. See Half deck, under Deck.
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The Collaborative International Dictionary of English v.0.48:

Deck \Deck\, n. [D. dek. See Deck, v.]
   1. The floorlike covering of the horizontal sections, or
      compartments, of a ship. Small vessels have only one deck;
      larger ships have two or three decks.
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   Note: The following are the more common names of the decks of
         vessels having more than one.
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   Berth deck (Navy), a deck next below the gun deck, where
      the hammocks of the crew are swung.

   Boiler deck (River Steamers), the deck on which the boilers
      are placed.

   Flush deck, any continuous, unbroken deck from stem to
      stern.

   Gun deck (Navy), a deck below the spar deck, on which the
      ship's guns are carried. If there are two gun decks, the
      upper one is called the main deck, the lower, the lower
      gun deck; if there are three, one is called the middle gun
      deck.

   Half-deck, that portion of the deck next below the spar
      deck which is between the mainmast and the cabin.

   Hurricane deck (River Steamers, etc.), the upper deck,
      usually a light deck, erected above the frame of the hull.


   Orlop deck, the deck or part of a deck where the cables are
      stowed, usually below the water line.

   Poop deck, the deck forming the roof of a poop or poop
      cabin, built on the upper deck and extending from the
      mizzenmast aft.

   Quarter-deck, the part of the upper deck abaft the
      mainmast, including the poop deck when there is one.

   Spar deck.
      (a) Same as the upper deck.
      (b) Sometimes a light deck fitted over the upper deck.

   Upper deck, the highest deck of the hull, extending from
      stem to stern.
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   2. (arch.) The upper part or top of a mansard roof or curb
      roof when made nearly flat.
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   3. (Railroad) The roof of a passenger car.
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   4. A pack or set of playing cards.
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            The king was slyly fingered from the deck. --Shak.
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   5. A heap or store. [Obs.]
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            Who . . . hath such trinkets
            Ready in the deck.                    --Massinger.
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   6. (A["e]ronautics) A main a["e]roplane surface, esp. of a
      biplane or multiplane.
      [Webster 1913 Suppl.]

   7. the portion of a bridge which serves as the roadway.
      [PJC]

   8. a flat platform adjacent to a house, usually without a
      roof; -- it is typically used for relaxing out of doors,
      outdoor cooking, or entertaining guests.
      [PJC]

   Between decks. See under Between.

   Deck bridge (Railroad Engineering), a bridge which carries
      the track upon the upper chords; -- distinguished from a
      through bridge, which carries the track upon the lower
      chords, between the girders.

   Deck curb (Arch.), a curb supporting a deck in roof
      construction.

   Deck floor (Arch.), a floor which serves also as a roof, as
      of a belfry or balcony.

   Deck hand, a sailor hired to help on the vessel's deck, but
      not expected to go aloft.

   Deck molding (Arch.), the molded finish of the edge of a
      deck, making the junction with the lower slope of the
      roof.

   Deck roof (Arch.), a nearly flat roof which is not
      surmounted by parapet walls.

   Deck transom (Shipbuilding), the transom into which the
      deck is framed.

   To clear the decks (Naut.), to remove every unnecessary
      incumbrance in preparation for battle; to prepare for
      action.

   To sweep the deck (Card Playing), to clear off all the
      stakes on the table by winning them.
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