1. An electric lamp in which the light comes from an electric discharge between two electrodes in a glass tube.
2. A lamp in which light is produced by an electric discharge between electrodes in a gas (or vapor) at low or high pressure.
3. A lamp that uses the transmission of an electric current through a gas or vapor to produce illumination. Neon, mercury and argon lamps are examples of electric-discharge lamps.
4. A lamp whose light is produced by current flow through a gas or vapor in a sealed glass enclosure.

Examples of these lamps include argon glow, mercury-vapor, neon glow, and sodium-vapor.