- An incandescent lamp that consists of a tungsten filament, a gas containing halogens, and an envelope of a high-temperature resistant material, such as quartz. The lamp is small compared with lamps of similar wattage. See also quartz lamp.
- A halogen lamp whose contained gas is iodine, or that of another halogen or mixture of halogens, and whose filament is composed of tungsten. The gas in these high-efficiency lamps reacts with the tungsten metal which evaporates, recycling the particles back onto the filament surface. Also called halogen lamp (2).