Definition of anion noun from the Oxford Advanced Learner's Dictionary



BrE BrE//ˈænaɪən//
; NAmE NAmE//ˈænaɪən//
(chemistry, physics) Molecules and matter
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an ion with a negative electrical charge compare cation See related entries: Molecules and matter Word Origin mid 19th cent.: from anode or ana- + ion.
See the Oxford Advanced American Dictionary entry: anion