D defs.my
Entry 3 senses Webster, 1913

Buoyancy

/boi'-ən-sē/ · Buoy·an·cy · IPA /ˈbɔɪ.ən.si/
01 n. The property of floating on the surface of a liquid, or in a fluid, as in the atmosphere; specific lightness, which is inversely as the wei…
pl. Buoyancies
  1. 1.
    The property of floating on the surface of a liquid, or in a fluid, as in the atmosphere; specific lightness, which is inversely as the weight compared with that of an equal volume of water.
  2. 2.
    The upward pressure exerted upon a floating body by a fluid, which is equal to the weight of the body; hence, also, the weight of a floating body, as measured by the volume of fluid displaced.(Physics)
    “Such are buoyancies or displacements of the different classes of her majesty's ships.” Eng. Cyc.
  3. 3.
    Cheerfulness; vivacity; liveliness; sprightliness; -- the opposite of heaviness; as, buoyancy of spirits.