Keel

From Middle English kele, from Old Norse kjÇ«lr.

Full definition of keel

(plural keels)

(nautical) A large beam along the underside of a shipâ€™s hull from bow to stern.
(nautical) Sometimes, a rigid, flat piece of material anchored to the lowest part of the hull of a ship to give it greater control and stability.
(nautical) A type of flat-bottomed boat.
A material similar to chalk or crayon used to mark pavement.
(zoology) The periphery of a whorl extended to form a more or less flattened plate; a prominent spiral ridge.
(botany) The two lowest petals of the corolla of a papilionaceous flower, united and enclosing the stamens and pistil; a carina.
A brewer's cooling vat.

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