keel

Etymology 1

From Middle English kele, from Old Norse kjǫlr, itself from Proto-Germanic *keluz, of uncertain origin. Displaced Old English ċēol from a related root. Distantly related to kile.

noun

1. (nautical) A large beam along the underside of a ship’s hull from bow to stern.
2. (nautical) A rigid, flat piece of material anchored to the lowest part of the hull of a ship to give it greater control and stability.
3. (aeronautics) In a dirigible, a construction similar in form and use to a ship's keel; in an aeroplane, a fin or fixed surface employed to increase stability and to hold the machine to its course.
4. (by extension) The rigid bottom part of something else, especially an iceberg.
   Coordinate term: bummock
   The most important ice features are the frequency and extent of downward projections (bummocks and ice keels) from the underside of the ice canopy (pack ice and enclosed water areas from the point of view of the submariner)[…] 1975, Nathaniel Bowditch, American Practical Navigator: An Epitome of Navigation, page 834
   Bill Roggensack, EBA Engineering Ltd.: So at the end of this particular simulation, presumably the keel of the iceberg is in contact with the seabed? / Chris Woodworth-Lynas: It is just in contact with the seabed. 1986, Environmental Studies Revolving Funds (Canada), C. F. M. Lewis, Federal Panel on Energy Research and Development (Canada), Gulf Canada Resources Inc, Ice Scour Workshop (1985 : Calgary, Alta.), Ice Scour and Seabed Engineering: Proceedings of a Workshop on Ice Scour Research
   Would he be able to break through the surface ice or would they ram into an ice keel extending down from the bottom of the ice pack that would rip their craft open like a mere sardine can? 2021-09-30, Kenneth Andrus, Arctic Menace, Babylon Books
5. (nautical) A type of flat-bottomed boat.
   The ladies remained at the house, while the men walked to the staith on the [River] Wear, and were shown the process of unloading the wagons into the keels by means of the coal-drop. 1948 January and February, “Notes and News: Duke of Wellington's Early Railway Journey”, in Railway Magazine, page 56
6. (zoology) The periphery of a whorl extended to form a more or less flattened plate; a prominent spiral ridge.
7. (botany) The two lowest petals of the corolla of a papilionaceous flower, united and enclosing the stamens and pistil; a carina.
   Vegetatively it is the nearest to H. translucens with its oblong-lanceolate leaves, with the margins and keel beset with pellucid teeth, but it differs and is characterised by the greyish-black quadrantly positioned globose flowers; […] 1985, Charles L. Scott, The Genus Haworthia (Liliaceae): A Taxonomic Revision, page 80

verb

1. (intransitive, followed by "over") to collapse, to fall
   He keeled over after having a stroke.
2. To traverse with a keel; to navigate.
3. To turn up the keel; to show the bottom.

Etymology 2

From Middle English kelen, from Old English cēlan (“to cool, to make or become cool”), from Proto-West Germanic *kōlijan, from Proto-Germanic *kōlijaną (“to cool”). Cognate with Saterland Frisian käile, köile (“to cool”), Dutch koelen (“to cool”), German Low German köhlen (“to cool”), German kühlen (“to cool”), Danish køle (“to cool”), Icelandic kæla (“to cool”).

verb

1. (transitive, obsolete) To cool; make cool; to cool by stirring or skimming in order to keep from boiling over.
   while greasy Joan doth keel the pot (Shakespeare)
2. (transitive, obsolete) To moderate the ardour or intensity of; assuage; to appease, pacify, or lessen.
3. (intransitive, obsolete) To become cool; cool down.

noun

1. (brewing) A broad, flat vessel used for cooling liquids; a brewer's cooling vat; a keelfat.

Etymology 3

Probably from Scottish Gaelic cìl (“ruddle”).

noun

1. (Scotland) Red chalk; ruddle.

verb

1. (Scotland, transitive) To mark with ruddle.

Etymology 4

Compare Scots kele, keil, keill (“to put to death, kill”).

verb

1. Pronunciation spelling of kill.