keel

A large beam along the underside of a ship’s hull from bow to stern.

I hear the noise about thy keel; ⁠I hear the bell struck in the night: ⁠I see the cabin-window bright; I see the sailor at the wheel.

A rigid, flat piece of material anchored to the lowest part of the hull of a ship to give it greater control and stability.

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.

The rigid bottom part of something else, especially an iceberg.

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)[…]

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.

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.

to collapse, to fall

He keeled over after having a stroke.

To traverse with a keel; to navigate.

To turn up the keel; to show the bottom.

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)

To moderate the ardour or intensity of; assuage; to appease, pacify, or lessen.

To become cool; cool down.