fluorescent lamp

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A lamp that produces visible light by fluorescence, especially a glass tube whose inner wall is coated with a material that fluoresces when an electrical current causes a vapor within the tube to discharge electrons.

Wiktionary

1. n. a gas-discharge lamp that uses fluorescence to produce visible light.

WordNet 3.0

1. n. lamp consisting of a tube coated on the inside with a fluorescent material; mercury vapor in the tube emits ultraviolet radiation that is converted to visible radiation by the fluorescent material