The Collaborative International Dictionary of English v.0.48:

Keel \Keel\, n. [Cf. AS. ce['o]l ship; akin to D. & G. kiel
   keel, OHG. chiol ship, Icel. kj[=o]ll, and perh. to Gr.
   gay^los a round-built Ph[oe]nician merchant vessel, gaylo`s
   bucket; cf. Skr. g[=o]la ball, round water vessel. But the
   meaning of the English word seems to come from Icel. kj["o]lr
   keel, akin to Sw. k["o]l, Dan. kj["o]l.]
   1. (Shipbuilding) A longitudinal timber, or series of timbers
      scarfed together, extending from stem to stern along the
      bottom of a vessel. It is the principal timber of the
      vessel, and, by means of the ribs attached on each side,
      supports the vessel's frame. In an iron vessel, a
      combination of plates supplies the place of the keel of a
      wooden ship. See Illust. of Keelson.
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   2. Fig.: The whole ship.
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   3. A barge or lighter, used on the Tyne for carrying coal
      from Newcastle; also, a barge load of coal, twenty-one
      tons, four cwt. [Eng.]
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   4. (Bot.) The two lowest petals of the corolla of a
      papilionaceous flower, united and inclosing the stamens
      and pistil; a carina. See Carina.
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   5. (Nat. Hist.) A projecting ridge along the middle of a flat
      or curved surface.
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   6. (Aeronautics) In a dirigible, a construction similar in
      form and use to a ship's keel; in an a["e]roplane, a fin
      or fixed surface employed to increase stability and to
      hold the machine to its course.
      [Webster 1913 Suppl.]

   Bilge keel (Naut.), a keel peculiar to ironclad vessels,
      extending only a portion of the length of the vessel under
      the bilges. --Ham. Nav. Encyc.

   False keel. See under False.

   Keel boat.
      (a) A covered freight boat, with a keel, but no sails,
          used on Western rivers. [U. S.]
      (b) A low, flat-bottomed freight boat. See Keel, n., 3.


   Keel piece, one of the timbers or sections of which a keel
      is composed.

   On even keel, in a level or horizontal position, so that
      the draught of water at the stern and the bow is the same.
      --Ham. Nav. Encyc.

   On an even keel a. & adv., steady; balanced; steadily.
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The Collaborative International Dictionary of English v.0.48:

Even \E"ven\, a. [AS. efen. efn; akin to OS. eban, D. even, OHG.
   eban, G. efen, Icel. jafn, Dan. jevn, Sw. j[aum]mn, Goth.
   ibns. Cf. Anent, Ebb.]
   1. Level, smooth, or equal in surface; not rough; free from
      irregularities; hence uniform in rate of motion of action;
      as, even ground; an even speed; an even course of conduct.
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   2. Equable; not easily ruffled or disturbed; calm; uniformly
      self-possessed; as, an even temper.
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   3. Parallel; on a level; reaching the same limit.
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            And shall lay thee even with the ground. --Luke xix.
                                                  44.
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   4. Balanced; adjusted; fair; equitable; impartial; just to
      both sides; owing nothing on either side; -- said of
      accounts, bargains, or persons indebted; as, our accounts
      are even; an even bargain.
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            To make the even truth in pleasure flow. --Shak.
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   5. Without an irregularity, flaw, or blemish; pure. "I know
      my life so even." --Shak.
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   6. Associate; fellow; of the same condition. [Obs.] "His even
      servant." --Wyclif (Matt. xviii. 29).
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   7. Not odd; capable of division by two without a remainder;
      -- said of numbers; as, 4 and 10 are even numbers.
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            Whether the number of the stars is even or odd.
                                                  --Jer. Taylor.
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   On even ground, with equal advantage.

   On even keel (Naut.), in a level or horizontal position.
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