[boi-uh n-see, boo-yuh n-see]


the power to float or rise in a fluid; relative lightness.
the power of supporting a body so that it floats; upward pressure exerted by the fluid in which a body is immersed.
lightness or resilience of spirit; cheerfulness.

Also buoy·ance.

Origin of buoyancy

First recorded in 1705–15; buoy(ant) + -ancy
Related formsnon·buoy·an·cy, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Related Words for buoyancy

resilience, elasticity

Examples from the Web for buoyancy

Contemporary Examples of buoyancy

Historical Examples of buoyancy

  • It may have been the gradient of the hills, but somehow her gait had lost something of its buoyancy.

    The Law-Breakers

    Ridgwell Cullum

  • He mingled a certain frowning impatience with the buoyancy of his smile.

    The Market-Place

    Harold Frederic

  • The buoyancy of their irresponsible natures was reasserting itself.

    The Golden Woman

    Ridgwell Cullum

  • But it was the light in their eyes, their grinning faces, the buoyancy of their gait that held him.

    The Golden Woman

    Ridgwell Cullum

  • They were young still, and the buoyancy of the country they had adopted was in both of them.

    The Greater Power

    Harold Bindloss

British Dictionary definitions for buoyancy



the ability to float in a liquid or to rise in a fluid
the property of a fluid to exert an upward force (upthrust) on a body that is wholly or partly submerged in it
the ability to recover quickly after setbacks; resilience
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for buoyancy

1713, from buoyant + -cy. Figurative sense (of spirits, etc.) is from 1819.

Online Etymology Dictionary, © 2010 Douglas Harper

buoyancy in Science



The upward force that a fluid exerts on an object that is less dense than itself. Buoyancy allows a boat to float on water and provides lift for balloons.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

buoyancy in Culture


The force that causes objects to float. According to the principle of Archimedes, when a solid is placed in a fluid (a liquid or a gas), it is subject to an upward force equal in magnitude to the weight of the fluid it has displaced.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.