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

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

The bacteria respired away the carbon and released nitrogen as ammonium. —Joshua Weitz, The Conversation, 13 Jan. 2026

This means that heavy elements like rock and metal are dissolved and encased in a thick mantle of metallic hydrogen enveloped in a massive atmospheric cloak of multi-colored clouds of ammonium hydrosulphide. —Joe Rao, Space.com, 7 Jan. 2026

Those materials include sodium perchlorate, ammonium perchlorate precursors and nitrocellulose, all key components in solid-fuel rocket motors. —Antonio María Delgado, Miami Herald, 30 Dec. 2025

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

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

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