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  1. Nautical. a central fore-and-aft structural member in the bottom of a hull, extending from the stem to the sternpost and having the floors or frames attached to it, usually at right angles: sometimes projecting from the bottom of the hull to provide stability.
  2. Literary. a ship or boat.
  3. a part corresponding to a ship's keel in some other structure, as in a dirigible balloon.
  4. (initial capital letter) Astronomy. the constellation Carina.
  5. Botany, Zoology. a longitudinal ridge, as on a leaf or bone; a carina.
  6. Also called brace molding. Architecture. a projecting molding the profile of which consists of two ogees symmetrically disposed about an arris or fillet.
verb (used with or without object)
  1. to turn or upset so as to bring the wrong side or part uppermost.
Verb Phrases
  1. keel over,
    1. to capsize or overturn.
    2. to fall as in a faint: Several cadets keeled over from the heat during the parade.
  1. on an even keel, in a state of balance; steady; steadily: The affairs of state are seldom on an even keel for long.

Origin of keel1

1325–75; 1895–1900 for def 8; Middle English kele < Old Norse kjǫlr; cognate with Old English cēol keel, ship; see keel2
Related formskeeled, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for keel over

keel over

verb (adverb)
  1. to turn upside down; capsize
  2. (intr) informal to collapse suddenly


  1. one of the main longitudinal structural members of a vessel to which the frames are fastened and that may extend into the water to provide lateral stability
  2. on an even keel well-balanced; steady
  3. any structure corresponding to or resembling the keel of a ship, such as the central member along the bottom of an aircraft fuselage
  4. biology a ridgelike part; carina
  5. a poetic word for ship
  1. to capsize
See also keel over
Derived Formskeel-less, adjective

Word Origin

C14: from Old Norse kjölr; related to Middle Dutch kiel, keel ²


noun Eastern British dialect
  1. a flat-bottomed vessel, esp one used for carrying coal
  2. a measure of coal equal to about 21 tons

Word Origin

C14 kele, from Middle Dutch kiel; compare Old English cēol ship


  1. red ochre stain used for marking sheep, timber, etc
verb (tr)
  1. to mark with this stain

Word Origin

Old English cēlan, from cōl cool


  1. an archaic word for cool

Word Origin

C15: probably from Scottish Gaelic cīl


  1. a fatal disease of young ducks, characterized by intestinal bleeding caused by Salmonella bacteria

Word Origin

C19: from keel 1; see keel over
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for keel over



"lowest timber of a ship or boat," mid-14c., probably from a Scandinavian source, cf. Old Norse kjölr "keel," Danish kjøl, Swedish köl, from Proto-Germanic *keluz, of uncertain origin. Some etymologists say this is unconnected with the keel that means "a ship, barge," which also is the root of Middle Dutch kiel "ship," Old English ceol "ship's prow," Old High German kiel, German Kiel "ship," but the two words have influenced each other. Barnhart, however, calls them cognates. This other word is said to be from Proto-Germanic *keula, from PIE *geul- "rounded vessel." Keel still is used locally in England and U.S. for "flat-bottomed boat," especially on the Tyne.



1838, American English, from keel (n.). To keel over (1876) is from the nautical image of a ship turning keel-up. Related: Keeled; keeling.



"to keep cool," from Middle English kelen, from Old English celan "to cool," from col "cool" (see cool). The form kele (from Old English colian) was used by Shakespeare, but it later was assimilated with the adjective form into the modern verb cool. Cognate with Dutch koelen, Old High German chuolen, German kühlen.

Online Etymology Dictionary, © 2010 Douglas Harper

Idioms and Phrases with keel over

keel over

Collapse, as if in a faint; also, faint. For example, When she heard the awful news, she keeled over. This term alludes to a vessel rolling on its keel and capsizing. [Mid-1800s]


In addition to the idiom beginning with keel

also see:

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.