buoyancy

American  

[boi-uhn-see, boo-yuhn-see] / ˈbɔɪ ən si, ˈbu jən si /

Also buoyance

noun

buoyancies plural

1. the power to float or rise in a fluid; relative lightness.

2. the power of supporting a body so that it floats; upward pressure exerted by the fluid in which a body is immersed.

3. lightness or resilience of spirit.

   Student well-being and buoyancy are especially important because of the relatively high incidence of depression and suicide.

---

buoyancy British  

/ ˈbɔɪənsɪ /

noun

1. the ability to float in a liquid or to rise in a fluid

2. the property of a fluid to exert an upward force (upthrust) on a body that is wholly or partly submerged in it

3. the ability to recover quickly after setbacks; resilience

4. cheerfulness

---

buoyancy Scientific  

/ boi′ən-sē /

1. 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.

---

buoyancy Cultural  

1. 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.

---

Other Word Forms

Derived Forms

• nonbuoyancy
  noun

Inflected Forms

Nouns

• buoyancies
  plural

Etymology

Origin of buoyancy

First recorded in 1705–15; buoy(ant) + -ancy

Explanation

Buoyancy is a quality that makes things float in water. It's also a type of happiness: if you're full of buoyancy, your mood is light and happy. This is a word with two main meanings that fit together well: Both kinds of buoyancy have to do with floating and staying up. The physical kind refers to objects that float instead of sinking in water, like a life raft or a buoy. The other kind of buoyancy is a happy mood, a feeling that nothing can get you down. So whenever you run into the word buoyancy, just think "staying afloat."

Example Sentences

Buoyancy and the touch of water on skin are magic, he said, but there’s science involved too.

From Los Angeles Times • Jan. 1, 2026

The test will take place in one of the largest pools in the world: Nasa's Neutral Buoyancy Laboratory at the Johnson Space Center in Houston, Texas.

From BBC • May 14, 2025

Rathjen recently spoke with Salon via Zoom about "Buoyancy."

From Salon • Sep. 9, 2020

No amount of underwater spacewalk training in NASA’s Neutral Buoyancy Lab can prepare you for these temperature shifts, he adds.

From National Geographic • Nov. 5, 2015

Buoyancy was provided for by having several tanks for the introduction of compressed air, and there was an emergency arrangement so that a collapsible aluminum container could be distended and filled with a powerful gas.

From Tom Swift and His Submarine Boat, or, under the Ocean for Sunken Treasure by Appleton, Victor [pseud.]

Related Words

• elasticity
• resilience