Arc Lamp: A bulb that produces light by an arc created between two electrodes inside a glass envelope that contains a gas.

Aspect Ratio: The width of a picture or projection screen in relation to its height, usually expressed in a “width x height” manner, i.e., 4x3 or 4:3.

Audience Blinders (a.k.a. Molefays): A fixture that contains multiple bulbs (usually PARs) that is pointed at the audience and bumped for accents or used to illuminate the crowd.

Barn Doors: A unit that is mounted at the front of a lighting fixture with adjustable doors that shapes the beam and helps control spill.

Barrel: The part of an ellipsoidal fixture that contains the lenses.

Batten: Metal pipes suspended in rows above a stage, used for the rigging of lighting and scenery.

Black Burst: A blank video signal that synchronizes video sources so they’re moving in step from one frame to the next.

Bump: A quick level change in lighting, usually to full.

Coffin Locks (a.k.a. Roto-Lock): A mortised connector used to couple stage platforms or scenic items together.

Color Temperature: The measurement in degrees on the Kelvin scale indicating the hue of a specific type of light source.

Component Video: An analog video signal using three conductors, one each for luminance (with sync and green reference), blue minus luminance and red minus luminance.

Composite Video: A single-channel analog video signal carrying all information.

Cyc Light: A wash fixture normally used in multiples to light up a cyclorama, or now more commonly any backdrop.

Cyclorama: A curved wall or curtain at the back (upstage) of a theater stage.

Dichroic: A glass filter that allows a limited range of color to pass through a light fixture while reflecting the other colors in the spectrum.

DMX512: The standard digital lighting protocol that can send 512 channels of control information to dimmers, automated lighting fixtures or special effects.

Dress Kit: Drapery surrounding a portable projection screen, helping control spill light and giving a finished appearance.

Ellipsoid Reflector Spotlight (a.k.a., Ellipsoidal, ERS, Profile or Leko): A spot stage lighting fixture with an ellipsoid shaped reflector that directs light through the barrel and lens, allowing focusing of the beam.

Footcandle (fc): A unit of measurement of illumination – one footcandle equals one lumen per square foot.

Gel: Common name for a color lighting filter.

Genlock: Synchronization of the video signals of multiple devices to a single source, like a black burst generator.

Gobo (a.k.a. Pattern): A glass or metal plate with a design etched or imprinted on its surface that can be projected when inserted into the pattern slot of an ERS type fixture.

Intelligent Light (a.k.a. Intel or Automated Light): A lighting fixture that can be controlled from a console that can pan, tilt, color or shape the light beam.

Jacks: Bracing frames attached to the back of scenic elements to keep them from falling over.

Keystone Error: An incorrect shape in a projected image when the projector is not located correctly in relation to the screen.

Lamp: Proper term for a light bulb. In show business also refers to the entire luminaire fixture.

Lumen (lm): A measure of the perceived power of light to the human eye.

Luminance: A measure of the brightness of a video display or signal.

NTSC (National Television System Committee): The video standard protocol in the U.S.

PAR Can: A common, basic stage lighting fixture that houses a PAR lamp.

Pin Spot: A very narrow beam lighting fixture.

Pipe & Base: Lighting stands using cast iron bases and threaded steel pipe for the upright.

Pipe & Drape: Aluminum pipe uprights and adjustable horizontal crossbars that hold up draperies and curtains at trade shows and events.

Pixel (short for Picture Element): The smallest addressable element used to build an image.

Pre-Rigged Truss: Truss sections that contain lighting fixtures and cabling for easy set up at an event.

Projector Throw Distance: The length from the lens of a projector to the screen necessary for a particular unit to produce an image of a specified size.

RGBHV (a.k.a. 5 Wire): A five-component analog video format that separates red, green, blue information and horizontal and vertical sync into five signals.

RGsB (a.k.a. Sync On Green): A three-component analog video signal comprised of a red channel, blue channel and a green channel with composite sync.

S-Video (a.k.a. Separated Video or Y/C): An analog format that separates brightness information (luminance or Y) from color information (chrominance or C) in a video signal.

Scaler: Stand-alone unit or a feature in a display device that changes the size of an image.

Scan Conversion: The process of changing the horizontal scan rate of one device to that of another.

Soft Patch: A system allowing control and diming/fixture channels to be assigned without following a set format.

Special: A stage light used to highlight a performer or scenic element.

Sync (Synchronization): Timing information to insure images display properly.

Universe: A group of 512 DMX channels.

Zip Strip: Originally a fixture from Altman and now a common name for any compact strip light that uses small MR16 sized bulbs.

Craig Leerman is senior contributing editor of ProSoundWeb and Live Sound International, and is the owner of Tech Works, a full-service production company in Las Vegas.