keel1

noun

• 1the lengthwise timber or steel structure along the base of a ship, supporting the framework of the whole, in some vessels extended downwards as a ridge to increase stability.
• literary a ship: to buy a new keel with my gold, And fill her with such things as she may hold

• 2 Zoology a ridge along the breastbone of many birds to which the flight muscles are attached; the carina.

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

verb

• (of a boat or ship) turn over on its side; capsize: it’s going to take more wind to make this boat keel over
• informal (of a person or thing) fall over; collapse: a wardrobe was about to keel over on top of him