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

How oxygen and nitrogen were kept away from that system remains a mystery. —Adam Harrington, CBS News, 23 Dec. 2025

The National Organization for Rare Disorders states that it is characterized by a complete or partial lack of the carbamoyl phosphate synthetase (CPS) enzyme, one of five that play a role in the breakdown and removal of nitrogen from the body. —Charlotte Phillipp, PEOPLE, 21 Dec. 2025

To confirm that nitrogen, rather than oxygen, was responsible for this behavior, the researchers reduced oxygen groups while keeping nitrogen intact. —Rupendra Brahambhatt, Interesting Engineering, 20 Dec. 2025

The fact that carbon monoxide gas has previously been detected in this system indicates these objects are rich in volatiles, substances such as hydrogen, nitrogen, oxygen and methane that easily turn gaseous at low temperatures. —Robert Lea, Space.com, 18 Dec. 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