liquid oxygen

American

noun

a clear, pale blue liquid obtained by compressing oxygen and then cooling it below its boiling point: used chiefly as an oxidizer in liquid rocket propellants.

liquid oxygen British

noun

Also called: lox. the clear pale blue liquid state of oxygen produced by liquefying air and allowing the nitrogen to evaporate: used in rocket fuels

"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

Etymology

Origin of liquid oxygen

First recorded in 1875–80

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

liquid oxygen

It uses liquid hydrogen and liquid oxygen, a more efficient propellant combination than the methane and oxygen used by Starship's Raptor engines.

From Science Daily ● Jul. 11, 2026

Liquid-fuel rockets, on the other hand, can be cycled on and off and combine an oxidizer, like cryogenic liquid oxygen, often with liquid hydrogen.

From The Wall Street Journal ● Jun. 14, 2026

The idea would be to launch several rockets, one carrying crew or cargo, and the others carrying tanks of liquid oxygen and liquid methane that would be offloaded through coupling.

From Barron's ● Jun. 12, 2026

During launches, the external tank carried propellants — liquid oxygen and liquid hydrogen — that powered the space shuttle’s three main engines to help bring the shuttle into orbit.

From Los Angeles Times ● Jan. 2, 2024

I have 50 liters of liquid oxygen in two 25-liter tanks here in the Hab.

From "The Martian" by Andy Weir

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023