Definitions

1. noun

A negatively charged ion that balances the positive charge of a positively charged ion in a compound, especially in a salt.

“The counterion stabilized the positively charged molecule, allowing it to dissolve in water.”

2. noun

In electrochemistry, an ion that has a charge of opposite sign to that of an electrode.

“The counterion played a crucial role in the electrochemical reaction, facilitating the transfer of electrons.”