1. The decomposition of a substance by passage of an electric current through it; for example, hair follicles may be destroyed with this procedure or the destruction of tumors with an electric current.
2. A process in which the passage of an electric current through an electrolytic solution or other suitable medium produces a chemical reaction; such as, that which occurs in a battery.
3. The process of splitting water into its components, hydrogen, and oxygen; by means of an electrical current.
4. Any process in which the passage of an electric current through a solution or medium produces a chemical reaction.
5. The chemical decomposition of a substance by the reactions that occur to its constituent ions at electrodes when an electric current is passed through the molten substance or, more often, through a solution of the substance.
6. The production of chemical changes by passing electric current from an electrode to an electrolyte, or the reverse of such action.

It is also used to separate isotopes, as in the concentration of deuterium, or heavy water, by the electrolysis of ordinary water.

7. One application of electrolysis is the permanent removal of body hair, including the hair roots, with an electronic instrument.

Although electrolysis is promoted as a permanent process, many people find that hair does grow back, although slowly, after electrolysis.

Electrolysis may be done by a dermatologist, by an electrolysis technician, or by a facial technologist or esthetician.