ammonium

American  

[uh-moh-nee-uhm] / əˈmoʊ ni əm /

noun

Chemistry.

1. the univalent ion, NH 4 + , or group, NH 4 , which plays the part of a metal in the salt formed when ammonia reacts with an acid.

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ammonium British  

/ əˈməʊnɪəm, -njəm /

noun

1. (modifier) of, consisting of, or containing the monovalent group NH 4 – or the ion NH 4 ⁺

   ammonium compounds

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ammonium Scientific  

/ ə-mō′nē-əm /

1. A positively charged ion, NH ₄, derived from ammonia and found in a wide variety of organic and inorganic compounds. Compounds of ammonium chemically resemble the alkali metals.

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Etymology

Origin of ammonium

< New Latin; see ammonia, -ium; coined by J. J. Berzelius in 1808

Compare meaning

How does ammonium compare to similar and commonly confused words? Explore the most common comparisons:

• ammonia vs. ammonium

Explanation

Ammonium is an ionic compound made of nitrogen and hydrogen, commonly found in household cleaners and fertilizers. Derived from ammonia, ammonium behaves like an alkali metal ion. This means that it can easily bond with other elements, making it versatile and effective in various applications. For example, ammonium is a key ingredient in cleaning products, where it helps break down dirt and grime, making surfaces shine. In fertilizers, ammonium provides essential nutrients that help plants grow strong and healthy.

Example Sentences

Ammonium not only helps these bacteria thrive but also nourishes algae and, by extension, the creatures that depend on them.

From Science Daily • Oct. 21, 2025

Ammonium nitrate is used mainly as a fertilizer.

From New York Times • May 21, 2023

Ammonium lauryl sulfate is a surfactant that can encourage infiltration of water into dried clay, and may make it easier to mechanically aerate clay soils.

From Seattle Times • Feb. 15, 2022

Ammonium nitrate will explode in certain circumstances, such as coming into contact with open flames or another ignition source, or being subject to very high temperatures.

From BBC • Sep. 3, 2021

Ammonium chloride is indicated in the earlier stages of the bronchitis.

From A System of Practical Medicine by American Authors, Vol. I Volume 1: Pathology and General Diseases by Various