The Collaborative International Dictionary of English v.0.48:

Keel \Keel\ (k[=e]l), v. t. & i. [AS. c[=e]lan to cool, fr.
   c[=o]l cool. See Cool.]
   To cool; to skim or stir. [Obs.]
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         While greasy Joan doth keel the pot.     --Shak.
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The Collaborative International Dictionary of English v.0.48:

Keel \Keel\, n.
   A brewer's cooling vat; a keelfat.
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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:

Keel \Keel\, v. i. [imp. & p. p. Keeled; p. pr. & vb. n.
   Keeling.]
   1. To traverse with a keel; to navigate.
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   2. To turn up the keel; to show the bottom.
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   To keel over, to upset; to capsize. [Colloq.]
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WordNet (r) 3.0 (2006):

keel
    n 1: a projection or ridge that suggests a keel
    2: the median ridge on the breastbone of birds that fly
    3: one of the main longitudinal beams (or plates) of the hull of
       a vessel; can extend vertically into the water to provide
       lateral stability
    v 1: walk as if unable to control one's movements; "The drunken
         man staggered into the room" [syn: stagger, reel,
         keel, lurch, swag, careen]

Moby Thesaurus II by Grady Ward, 1.0:

76 Moby Thesaurus words for "keel":
   argosy, ascend, bank, bark, base, baseboard, basement, be lost,
   boat, bottom, bucket, cant, capsize, careen, chassis, climb, craft,
   dado, decline, descend, dip, drop, fall, fall away, fall off, foot,
   footing, foundation, founder, frame, go down, go downhill,
   go uphill, grade, hooker, hulk, hull, incline, keel over, lean,
   leviathan, list, mopboard, nadir, overset, overturn, packet, pitch,
   pitchpole, rake, retreat, rise, scuttle, shelve, ship, shoemold,
   sidle, sink, slant, slope, sole, somersault, swag, sway, tilt, tip,
   toe, tub, turn over, turn turtle, uprise, upset, upset the boat,
   vessel, wainscot, watercraft