anion
n. countablen. a negatively charged particle in a chemical solution. It moves toward the positive side of an electric current.
n. an atom or molecule that has gained one or more electrons, giving it a negative charge. It is attracted to the anode in an electrolytic cell.
Chloride is a common anion found in salt water.
In the electrolysis of water, the anion moves toward the positive electrode while the cation moves toward the negative one.
The stability of the resulting compound depends on the relative sizes and charges of the anion and cation, as smaller ions with higher charges tend to form more robust ionic bonds.
Learned borrowing from Ancient Greek ἀνιόν (anión, “(thing) going up”), neuter present participle of ἄνειμι (áneimi, “go up”), from ἀνά (aná, “up”) + εἶμι (eîmi, “go”). Coined by English polymath William Whewell in 1834 for Michael Faraday, who introduced it later that year. By surface analysis, an- (“up, away, forward”) + ion.