1. An electrochemical cell in which the reactions are driven by the use of an external potential greater than the thermodynamic or reversible potential of the cell.
2. A cell consisting of electrodes immersed in an electrolyte solution, for carrying out electrolysis.
3. The electrolyte, its container, and the electrodes used in electrolysis.
4. A cell containing an electrolyte through which an externally generated electric current is passed by a system of electrodes in order to produce an electrochemical reaction which produces an electromotive force.

It can be used to store electric energy for use on demand, as in a storage cell; to generate electric energy, as in a dry cell; or to produce a desired electrochemical reaction when electric energy is applied.