metacenter

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The intersection of vertical lines through the center of buoyancy of a floating body when it is at equilibrium and when it is floating at an angle. The location of the metacenter is an indication of the stability of a floating body.

Century Dictionary and Cyclopedia

1. n. The point at which an upward thrust could be equivalent to the pressure of water upon a floating body which has received a slight rotational displacement about one of the principal axes of its section of flotation. The equilibrium is stable or unstable according as the metacenter is above or below the center of gravity. The term is specifically applied to the point where the vertical line passing through the center of buoyancy of a ship, in the position of equilibrium, meets the vertical drawn through the new center of buoyancy when the ship is slightly listed to one side or the other. The term was introduced into hydrostatics by Pierre Bouguer, a French geodesist (1698–1758). Also called center of cavity.
2. n. In biology, an organism or an organ which, while one of the descendants from an archetype, itself becomes a new archetype around which new divergent or apocentric modifications are produced.

Wiktionary

1. n. physics, shipbuilding A midway point between a ship's centre of buoyancy when upright and its centre of buoyancy when tilted; it must be above the centre of gravity to enable a tilting ship to return to an upright position.

GNU Webster's 1913

1. n. (Hydrostatics) The point of intersection of a vertical line through the center of gravity of the fluid displaced by a floating body which is tipped through a small angle from its position of equilibrium, and the inclined line which was vertical through the center of gravity of the body when in equilibrium.

WordNet 3.0

1. n. (shipbuilding) the point of intersection between two vertical lines, one line through the center of buoyancy of the hull of a ship in equilibrium and the other line through the center of buoyancy of the hull when the ship is inclined to one side; the distance of this intersection above the center of gravity is an indication of the stability of the ship