keel

Concise Oxford English Dictionary © 2008 Oxford University Press:
keel1

▶noun

• 1 a lengthwise structure along the base of a ship, in some vessels extended downwards as a ridge to increase stability.

• 2 Zoology a central ridge along the back or convex surface of an organ or structure.

• 3 Botany a prow-shaped pair of petals present in flowers of the pea family.

▶verb (keel over)

• 1 (of a boat or ship) turn over on its side; capsize.

• 2 fall over.

– derivatives
keeled adjective,
keelless adjective.

– origin ME: from ON kjǫlr, of Gmc origin.

Concise Oxford English Dictionary © 2008 Oxford University Press:
keel2

▶noun Brit. a flat-bottomed boat of a kind formerly used on the Rivers Tyne and Wear for loading coal-transporting ships.

– origin ME: from Mid. Low Ger. kēl, MDu. kiel ‘ship, boat’.