co-ions

https://dx.doi.org/10.1351/goldbook.C01141
  1. Ions of low relative molecular mass with a charge of the same sign as that of a given colloidal ion.
    Source:
    PAC, 1972, 31, 577 (Manual of Symbols and Terminology for Physicochemical Quantities and Units, AppendixII: Definitions, Terminology and Symbols in Colloid and Surface Chemistry) on page 607
  2. In an ion exchanger, mobile ionic species with a charge of the same sign as the fixed ions.
Source: