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
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Each of the five experiments produced carbon monoxide, cyanate, and ammonium — compounds that were detected in Enceladus' plumes by NASA's Cassini spacecraft in 2005.
—
Sharmila Kuthunur, Space.com, 12 Sep. 2025
Two additional organic ammonium salts — N,N-dimethyloctylammonium iodide (DMOAI) and phenethylammonium chloride (PEACl) — stabilised the material’s ions, stopping them from separating into different phases that hurt efficiency.
—Aamir Khollam, Interesting Engineering, 11 Aug. 2025
Many Japanese straightening treatments do not include bisphenol A and formaldehyde, but do include ammonium thioglycolate which is a chemical that can cause significant skin irritation and damage scalp health.
—Cierra Black, Essence, 17 July 2025
Hartford Courant There are other factors that can affect calcium uptake by the plant, such as high concentrations of ammonium, potassium, and magnesium in the soil.
—Nora Doonan, Hartford Courant, 14 June 2025
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Sharmila Kuthunur, Space.com, 12 Sep. 2025
Two additional organic ammonium salts — N,N-dimethyloctylammonium iodide (DMOAI) and phenethylammonium chloride (PEACl) — stabilised the material’s ions, stopping them from separating into different phases that hurt efficiency.
—Aamir Khollam, Interesting Engineering, 11 Aug. 2025
Many Japanese straightening treatments do not include bisphenol A and formaldehyde, but do include ammonium thioglycolate which is a chemical that can cause significant skin irritation and damage scalp health.
—Cierra Black, Essence, 17 July 2025
Hartford Courant There are other factors that can affect calcium uptake by the plant, such as high concentrations of ammonium, potassium, and magnesium in the soil.
—Nora Doonan, Hartford Courant, 14 June 2025
See All Example Sentences for ammonium
Cite this Entry
“Ammonium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ammonium. Accessed 17 Sep. 2025.
Copy CitationKids 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
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