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.

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

From Barron's • Feb. 3, 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

But Swedish submarines have liquid oxygen stored in tanks on board to run the diesel engines underwater to recharge the batteries, so they can stay submerged for longer and reduce the risk of detection.

From Reuters • Jul. 3, 2023

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