Noun
A movable or sliding keel formed of a broad board or slab of wood or metal which may be raised into a water-tight case amidships, when in shallow water, or may be lowered to increase the area of lateral resistance and prevent leeway when the vessel is beating to windward. It is used in vessels of all sizes along the coast of the United States
Source: Webster's dictionaryA boat with no centreboard will instead have a permanent keel, some other form of underwater foil, or even the hull itself which serves the same purpose. Source: Internet
Hull types Monohull yachts are typically fitted with a fixed keel or a centreboard (adjustable keel) below the waterline to counterbalance the overturning force of wind on the vessel's sails. Source: Internet
The windward performance of the ship was poor by modern standards as there was no centreboard, deep keel or leeboard. Source: Internet