- A low-pressure mercury electric-discharge lamp in which a phosphor coating on the inside of the tube transforms some of the ultraviolet energy generated by the discharge into visible light.
- A gas-discharge lamp whose light is produced through fluorescence. Such a lamp usually consists of a tube coated with a fluorescent substance, and contains mercury vapor. A current passing through the tube excites the vapor, whose ultraviolet emissions excite the coating, which in turn emits visible light. Also called fluorescent tube.
- synonymfluorescent tube