nitrogen

noun

ni·​tro·​gen ˈnī-trə-jən 

: a nonmetallic chemical element with atomic number 7 that under standard conditions is a colorless, odorless, inert gas, that constitutes 78 percent of the Earth's atmosphere, and that is used especially in the industrial synthesis of ammonia, as a component of inert atmospheres, and in liquid form as a refrigerant

—often used before another noun

the nitrogen cycle

nitrogen fertilizer

see Chemical Elements Table

Examples of nitrogen in a Sentence

Recent Examples on the Web

High-speed subatomic particles raining down from solar storms slam into the nitrogen in our atmosphere to create an isotope called beryllium 10, or Be-10, which can be captured in polar ice after falling to Earth’s surface. —Phil Plait, Scientific American, 1 May 2025

Landry has made clear his intention to carry out these death sentences as soon as possible, having recently approved the use of nitrogen gas, a controversial method allowed in only three other states. —Richard A. Webster, ProPublica, 25 Apr. 2025

Alabama has also carried out four nitrogen gas executions in recent months, the first state to use that method. —CBS News, 23 Apr. 2025

Unless someone inside the federal government continues to ensure the liquid nitrogen doesn’t totally evaporate, the samples will eventually defrost and begin to rot, according to three staff researchers who work with such materials. —Caroline Haskins, Wired News, 17 Apr. 2025

Word History

Etymology

French nitrogène, from nitre niter + -gène -gen

First Known Use

1791, in the meaning defined above

Phrases Containing nitrogen

• nitrogen balance
• nitrogen cycle
• nitrogen dioxide
• nitrogen fixation
• nitrogen-fixer
• nitrogen-fixing
• nitrogen mustard
• nitrogen narcosis
• nitrogen oxide
• nitrogen tetroxide

Kids Definition

nitrogen

noun

ni·​tro·​gen ˈnī-trə-jən 

: a colorless tasteless odorless element that occurs as a gas which makes up 78 percent of the atmosphere and that forms a part of all living tissues see element

nitrogenous

nī-ˈträj-ə-nəs 

adjective

Medical Definition

nitrogen

noun

ni·​tro·​gen ˈnī-trə-jən 

: a common nonmetallic element that in the free form is normally a colorless odorless tasteless insoluble inert diatomic gas comprising 78 percent of the atmosphere by volume and that in the combined form is a constituent of biologically important compounds (as proteins, nucleic acids, and alkaloids) and hence of all living cells as well as of industrially important substances (as cyanides, fertilizers, dyes, and antibiotics)

—symbol N see Chemical Elements Table