1. a type of lamp in which an electrical gas discharge is maintained in a tube with a thin layer of phosphor on its inside surface. The gas, which is often mercury vapour, emits ultraviolet radiation causing the phosphor to fluoresce
2. a type of lamp in which an electrical discharge is maintained in a tube containinga gas such as neon, mercury vapour, or sodium vapour at low pressure. Gas atoms in the discharge are struck by electrons and fluoresce