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keel 1 (kēl)
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n.
1. Nautical
a. The principal structural member of a boat or ship, running along the center of the hull from bow to stern, to which the ribs are attached.
b. A projecting ridge or fin on the bottom of the hull of a boat or ship that improves directional control and is often weighted for added stability.
2. The principal structural member of an aircraft, resembling a ship's keel in shape and function.
3. A structure, such as the breastbone of a bird, that resembles a ship's keel in function or shape.
4. A pair of united petals in certain flowers, as those of many members of the pea family.
intr. & tr.v. keeled, keel·ing, keels
Nautical
To capsize or cause to capsize.
Phrasal Verb:
keel over
To collapse or fall into or as if into a faint.

[Middle English kele, from Old Norse kjölr.]

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
 
keel 2 (kēl)
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n.
1. Nautical
a. A sail-powered barge, especially one historically used on the rivers of northern England.
b. The load capacity of this barge.
2. A British unit of weight formerly used for coal, equal to about 21.2 long tons.

[Middle English kele, from Middle Dutch kiel.]

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
 
keel 3 (kēl)
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tr.v. keeled, keel·ing, keels
Chiefly British
To make cool.

[Middle English kelen, from Old English cēlan, to cool; see gel- in the Appendix of Indo-European roots.]

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
 

Indo-European & Semitic Roots Appendices

    Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

    Indo-European Roots

    Semitic Roots

    The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.