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

And, much like Earth’s atmosphere, Titan’s air is mostly nitrogen, albeit with small and distinctly unearthly amounts of methane and hydrogen. —Phil Plait, Scientific American, 10 Apr. 2026

The key fertilizer urea is up 25% to 30%, with nitrogen and potassium fertilizer costs similarly elevated, just as farmers are receiving their lowest cost per bushel in 17 crop years. —Nick Lichtenberg, Fortune, 10 Apr. 2026

What’s more, onions and other alliums have natural antibacterial properties that may inhibit the nitrogen-fixing bacteria on the roots of legume plants. —Lauren Landers, Better Homes & Gardens, 9 Apr. 2026

In that case, drought and limited water supply might be more important than shortages of nitrogen. —Sam Meredith, CNBC, 9 Apr. 2026

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