Definition of ion in English:


Line breaks: ion
Pronunciation: /ˈʌɪən


  • An atom or molecule with a net electric charge due to the loss or gain of one or more electrons: [with modifier]: hydrogen ions a sulphate ion See also cation, anion.
    More example sentences
    • Some compounds have polyatomic ions, where the ion is composed of two or more atoms.
    • The charge on the complex ion is the sum of the charges on the metal ion and the ligands.
    • At that stage, the electrons and ions combined into neutral atoms that no longer scattered the radiation.


mid 19th century: from Greek, neuter present participle of ienai 'go'.

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