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

Keeping super-cold liquid oxygen and methane stable in the vacuum of space, then transferring them between spacecraft, is one of the most demanding engineering challenges in the programme.

From BBC ● Apr. 10, 2026

The two-day test included filling the Space Launch System rocket with propellants, liquid hydrogen and liquid oxygen.

From Barron's ● Feb. 3, 2026

Filled with kerosene fuel now, plus the super-cool liquid oxygen and hydrogen, it was steaming in the sunshine.

From "Flying to the Moon: An Astronaut's Story" by Michael Collins

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