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

Subsequent lab tests revealed that the gas consisted almost entirely of pure hydrogen, accompanied only by trace amounts of nitrogen and methane. — Aman Tripathi, Interesting Engineering, 20 Aug. 2026

The suit against the ethanol plant also alleged some excess discharges of chlorine and nitrogen ammonia. — Adriana Pérez, Chicago Tribune, 20 Aug. 2026

Titan’s nitrogen-rich atmosphere is four times denser than Earth’s, allowing the car-sized Dragonfly drone’s eight rotors to easily fly between promising landing sites every Titan day (16 Earth days) to collect and study samples. — Jamie Carter, Forbes.com, 18 Aug. 2026

Liquids are lower in nitrogen and low on the salt index, so there’s less risk of burning. — Lee Wallender, The Spruce, 15 Aug. 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