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

Second, adding synthetic fertilizers rich in phosphorus or nitrogen can disrupt the harmonious partnership between plants and microbes. — Esther Ndumi Ngumbi, The Conversation, 8 July 2026

Those living roots carry minerals down into the earth to create a thriving subterranean ecosystem–fungi, earthworms, nitrogen–biodiversity–on this storied 1,000 acre plot of land; the largest tea farm in Korea on this tiny island. — Andrew Watman, Forbes.com, 8 July 2026

Excessive amounts of nitrogen and phosphorus from synthetic fertilizers and cow manure are then carried into the river by water and sediment runoff. — Hannah Smith updated July 8, Idaho Statesman, 8 July 2026

Nitrogen nitrogen applied early in the growing season helps develop leaves and strong stems. — Karen Brewer Grossman, Southern Living, 7 July 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