The principal piece of timber in a ship, which is usually first laid on the blocks in building; it supports and unites the whole fabric, since the stem and stern posts which are elevated on its ends, are, in some measure, a continuation of the keel, and serve to connect and enclose the extremities of the sides by transoms, as the keel forms and unites the bottom by timbers.

False-keel is a strong thick piece of timber bolted to the bottom of the keel, which is very useful in preserving its lower side; in large ships of war the false keel is composed of two pieces called the upper and lower false keels.

Keel is also a name given to a low, flat bottomed vessel, used in the river Tyne to bring the coals down from Newcastle for loading the colliers; hence a collier is said to carry so many keels.