ammonium

noun

am·​mo·​ni·​um ə-ˈmō-nē-əm 

: an ion NH₄⁺ derived from ammonia by combination with a hydrogen ion and known in compounds (such as salts) that resemble in properties the compounds of the alkali metals

Examples of ammonium in a Sentence

Recent Examples on the Web

Feeding the orbs To test how LiPfe sustains itself, Jobson’s team exposed its explants to isotopically labeled amino acids and ammonium. —Jacek Krywko, ArsTechnica, 29 May 2026

Chiang’s team used a liquid reagent made of water and ammonium fluoride — the active chemical in glass etchant — to do the exact opposite. —Mrigakshi Dixit, Interesting Engineering, 28 May 2026

The mineral, known as struvite, is a crystalline, colorless ammonium magnesium phosphate that has long been known for its flame-retardant qualities. —Ben Coxworth march 20, New Atlas, 20 Mar. 2026

On the day the hotel in Beirut was due to launch in August 2020, an ammonium-nitrate explosion tore through the city, bringing much of the area to rubble and tragically killing more than 200 people. —Condé Nast, Condé Nast Traveler, 27 Jan. 2026

Word History

Etymology

New Latin, from ammonia

First Known Use

1808, in the meaning defined above

Phrases Containing ammonium

• ammonium carbonate
• ammonium chloride
• ammonium cyanate
• ammonium hydroxide
• ammonium nitrate
• ammonium phosphate
• ammonium sulfate
• ferric ammonium citrate
• quaternary ammonium compound

Rhymes for ammonium

• conium
• carbonium
• harmonium
• meconium
• phosphonium
• plutonium
• polonium
• stramonium
• zirconium
• diazonium
• pandemonium
• pelargonium

Kids Definition

ammonium

noun

am·​mo·​ni·​um ə-ˈmō-nē-əm 

: an ion that comes from the combination of ammonia with a hydrogen ion

Medical Definition

ammonium

noun

am·​mo·​ni·​um ə-ˈmō-nē-əm 

: an ion NH₄⁺ derived from ammonia by combination with a hydrogen ion and known in organic compounds (as quaternary ammonium compounds) and in compounds (as salts) that resemble in properties the compounds of the alkali metals