Three-layered glass consisting of clear, opal, or colored sandwiched between clear, all fused together. Triplex glass provides more luster and diffusion than homogenous colored or opal glass.

Metal used to make the wire filament of incandescent lamps.

Single-ended compact fluorescent lamp with the tube bent into a very tight “U” shape.

Linear, double-ended fluorescent lamp, usually T8 or T12, bent into a “U” shape.

Underwriters’ Laboratories. A not-for-profit organization that works with the National Electrical Code to develop standards for electrical devices, wiring, and lighting fixtures. UL also tests fixtures and materials for compliance with the standards and lists fixtures for various applications, such as wet locations.

Detects motion or occupancy by radiating high-frequency sound waves and noting any disturbance in the reflected waves. Ultrasonic sensors can detect motion over partial-height partitions because the sound waves bounce off the room surfaces but can be fooled rustling curtains or small animals.

Also known as UV. This is light beyond the visible spectrum, having wavelengths from 10-380 nanometers.

Common name for a plain track light that accepts a wide range of line voltage reflectorized lamps.

Fixture installed behind a longitudinal shielding member mounted over a window or along a wall; light is distributed up and down, usually fluorescent.