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

The remaining elements include phosphorus, potassium, and nitrogen, which are key ingredients in fertilizers, according to researchers. —Prabhat Ranjan Mishra, Interesting Engineering, 23 Oct. 2025

Since orange trees are heavy feeders, look for a fertilizer that contains more nitrogen, such as a 2-1-1 or 3-1-1 nitrogen-phosphorus-potassium (NPK) ratio, as well as micro nutrients like magnesium, zinc, and iron. —Karen Brewer Grossman, Southern Living, 22 Oct. 2025

While almost every living organism possesses an excretory system, most reptiles don’t eliminate excess nitrogen-containing waste in the form of liquid urine. —Andrew Paul, Popular Science, 22 Oct. 2025

In response to the concerns, one Ohio official told lawmakers considering the method that nitrogen gas executions may very well be painful, according to reporting by the Ohio Capital Journal. —Amanda Lee Myers, USA Today, 22 Oct. 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