anion

noun

an·​ion ˈa-ˌnī-ən 

: the ion in an electrolyzed solution that migrates to the anode

broadly : a negatively charged ion

Examples of anion in a Sentence

Recent Examples on the Web

Changing the catalyst at the atomic level The catalyst was developed for anion exchange membrane water electrolysis, or AEMWE, a technology that produces hydrogen by splitting water under alkaline conditions. — Bojan Stojkovski, Interesting Engineering, 22 Aug. 2026

Borates are oxyanions; if ions are atoms or molecules that have a positive electrical charge, then anions have an overall negative electrical charge. — Keith Cooper, Space.com, 5 Jan. 2026

So, when her doctor messaged her the next day that her overall tests were fine, Miller wrote back to ask about the elevated carbon dioxide and low anion gap listed in the report. — Kate Ruder, jsonline.com, 17 Sep. 2025

Word History

Etymology

Greek, neuter of aniōn, present participle of anienai to go up, from ana- + ienai to go — more at issue entry 1

First Known Use

1834, in the meaning defined above

Rhymes for anion

• banyan
• canyon
• carbanion
• companion

Kids Definition

anion

noun

an·​ion ˈan-ˌī-ən 

: a negatively charged ion

Medical Definition

anion

noun

an·​ion ˈan-ˌī-ən 

: the ion in an electrolyzed solution that migrates to the anode

broadly : a negatively charged ion