generally any of several compounds comprised of carbon, fluorine, chlorine, and hydrogen, used chiefly as refrigerants and as blowing agents in plastic foams. Compare fluorocar­bon; halocarbon 

1. complete path of an electric current in or into a building, including usually the source of electric energy.

specially constructed, enclosed area environmental­ly controlled with respect to airborne particulates, tempera­ture, humidity, air pressure, air pressure flow patterns, air motion, vibration, viable organisms, and lighting.

in a clean room, the surface of the work part to be protected from particulate contamination.

1. space in a cylinder not occupied by the piston at the end of the compression stroke or the volume of gas remaining in a cylinder at the same point, measured in percentage of cylinder volume at the end of the expansion stroke.

2. clearance for maintenance or repair; the distance between the item requiring maintenance and the closest interfering surface.

non‑SI unit of clothing insulation, defined as the thermal insulation necessary to keep a sitting person comfortable in normally ventilated room at 70°F (21°C) and 50% relative humidity. In physical terms, the thermal resistance of one clo = .88°F·ft²·h/Btu (0.155 K^.m²/W).