ˈīən also ˈīˌän noun
( -s )
Etymology: Greek, neuter of iōn, present participle of ienai to go — more at issue
1. : an atom or group of atoms when combined in a radical or molecule that carries a positive or negative electric charge as a result of having lost or gained one or more electrons and that may exist in solution usually in combination with molecules of the solvent or out of solution, that may be formed during electrolysis and migrate to the electrode of opposite charge, or that may be formed in a gas and be capable of carrying an electric current through the gas — see anion , cation ; compare hydrogen ion
2. : a free electron or other charged subatomic particle