Glossary of Theatre Terms

AIR CASTER: A device which consists of a neoprene "O" (which inflates to create a seal with the floor) and a plenum chamber in the centre of the "O", in which air pressure builds up to exceed the load, thereby causing the device to rise, break the seal and float the device. Properties include almost frictionless horizontal movement, firm contact with the floor when unit settles in place. They require a very smooth nonporous surface.
AMPHITHEATRE: A circular or oval open-air theatre with a large, often semi-circular, raked seating area that slopes down to the stage. Originally built in ancient Greece and Rome for spectator sports, games and dramas.
APRON: The area of the stage between the proscenium line and the downstage (audience) edge of the stage. Also called the FORESTAGE.
ARBOR PIT: A pit located under the path of the flying system counterweights carriages, or arbors, to allow the arbors to go below the level of the stage floor and the battens to fly out higher than if the travel ended at the stage floor.
ARBOUR: A metal frame that holds the counterweights used to balance the weight of flown scenery. Also referred to as the arbour cradle or carriage. See COUNTERWEIGHTS and FLY.
AUDITORIUM: The area where the audience is seated. Also called the HOUSE.
BACKSTAGE: All production support areas out of sight of the audience.
BALCONY LIGHTS: Lights mounted on or on the front of the balcony, used to light the downstage areas.
BARNDOOR: A type of framing device for lighting instruments where two or four hinged metal pieces are mounted on the front of a lamp. Used to adjust and define the shape and size of the beam of light.
BATTEN: A steel pipe used to support scenery, curtains and lights. Usually suspended from the grid or roof structure.
BELAYING PIN: A wood or metal pin designed to be inserted into a hole in a pin rail to which running rigging is secured. See PIN RAIL.
BLACKS: 1) Any black drapes, permanently or temporarily rigged. Used for masking offstage areas. 2) The black clothing worn by stage managers and stage crew so as not to be seen by the audience.
BLOCK: A pulley or several pulleys in a frame. See PULLEY.
BOOM: Pipe mounted horizontally upon which to hang lights.
BOOMERANG: 1) A colour changer on the front of a light. 2) A multi-level moveable platform for workmen, frequently used by painters.
BORDER: Strips of fabric hung horizontally above the stage to mask overhead fly space and equipment.
BORDERLIGHT: A striplight (usually in 6" sections), usually as long as the proscenium is wide, hung from overhead and used for general illumination. Frequently found in older theatres hung every 10-12 feet.
BOX: Private, enclosed seating area, usually located at both sides of the stage in front of the proscenium arch.
BOX BOOM: Pipe rigged from the boxes on which lighting instruments can be hung to create sidelights.
BOX TRUSS: Rigging component used for support lights or drapes, usually in 12", 16", or 20" square shape.
CATWALK: Structural walkway above the house and/or stage that provides access for personnel to lighting equipment, rigging, or other servicing needs. Also typically used as a place to fasten lighting instruments.
CENTRE LINE: Imaginary line through the centre of the stage and auditorium, drawn from the upstage centre point of the stage to the centre point of the back of the auditorium.
CHAIN HOIST: Device for lifting scenery and lighting equipment, rigged to fixed points. Often used for lifting lighting truss into position (for touring shows or concerts).
CHAIN MOTOR: Portable, motorized hoisting device.
COMPANY SWITCH: Power disconnect with Cam-Lok connections for touring or travelling shows.
COUNTERWEIGHT RIGGING SYSTEM: A device for flying scenery by the use of weights, pulleys, blocks, ropes and arbors. It operates by using weights to offset the weight of the scenery and thus cause the scenery to rise or "fly". See FLY.
COUNTERWEIGHTS: The weights placed in an arbour or carriage and used to counterbalance loads placed on the battens that are moved vertically.
CUE: A visual or audible signal from the stage manager to execute a predetermined change of lights, sound or scenery, or to indicate an actor entrance.
CUT DROP: A drop into which patterns or designs have been cut.
CYCLORAMA: A large cloth curtain or plaster wall, either in one piece (preferred) or in sections, hung either flat or in a U-shape, usually in the most upstage position. Frequently white or light blue in colour and commonly used as a backdrop for lights and projections. Often referred to as the "CYC" (pronounced "psych").
DEAD HUNG: Battens or similar equipment that is permanently supported from the grid and cannot be easily raised or lowered as it is rigged without a counterweight.
DIMMER: Any means for controlling the light output from a lighting instrument.
DOUBLE PURCHASE COUNTERWEIGHT SYSTEM: An arrangement of pulleys and cables used to reduce the travel distance of a counterweight carriage or arbour. Requires twice the counterweight for a given load as a single purchase system and the batten travel is twice the arbour travel.
DOWN LIGHT: Light focused straight down onto the performing area.
DOWNSTAGE: The area of the stage closest to the audience.
DROP: A large unframed piece of material hung from a batten and with a lighter batten or chain at the bottom to keep it free of wrinkles. Often has a pictorial scene painted on it.
DROP WIRE (OR STINGER): The vertical wire rope used for rigging or suspending an object from a "rigging point". Often provided by a venue for their client to fix to (to maintain control over rigging practices).
EFFECTS MACHINE: A lens projection instrument designed to project moving effects.
ELLISPOIDAL: A type of spotlight that uses an ellipsoidal reflector. They are the most commonly-used type of theatre light as they can be focused and adjusted in very specific ways. (Short for ellipsoidal reflector spot light)
FIRE CURTAIN: A non-flammable curtain immediately behind the proscenium, contained in the smoke pocket, used to protect the audience from possible smoke and fire originating from the stage. Also called a SAFETY CURTAIN.
FIRE CURTAIN: A non-flammable curtain immediately behind the proscenium, contained in the smoke pocket, used to protect the audience from possible smoke and fire originating from the stage. Also called a SAFETY CURTAIN.
FLAT: A unit of scenery. Usually a rectangular frame of lumber covered in canvas or muslin.
FLIES: The space above the stage for flying scenery. See FLY LOFT.
FLY: To move scenery or similar devices vertically on the stage.
FLY GALLERY: A platform attached to the side wall of the stage from which the rigging devices are operated. Also called a fly floor.
FLY LOFT: The space between the top of the proscenium and the grid where scenery items are stored when not being flown onto the stage.
FLY RAIL: The area where the flying system is operated (before counterweight systems, this was the structure where the fly lines/ropes were tied off to hold scenery and other flown equipment in position).
FOH (FRONT OF HOUSE): Every part of the theatre on the audience side of the proscenium line, including foyer/lobby areas open to the general public, forestage, and house.
FOLLOWSPOT: A spotlight designed for following the movements of a performer.
FORESTAGE: The area of the stage between the proscenium line and the downstage (audience) edge of the stage. Also called the APRON.
FRESNEL: A type of spotlight that uses a lens called a "Fresnel". Generally used for colour washes as the edges are always soft.
GALLERY: Catwalk over the stage area.
GEL: General term which has come to mean any type of colour media for lights.
GERMANS (GERMAN MASKING): Using flats or drapes running upstage/downstage to mask both sides and the upstage wall of the stage.
GOBO: A metal plate with a shaped opening, placed inside a spotlight to shape the beams into particular patterns.
GREEN ROOM: Room close to the stage used by the performers to eat, prepare, wait, etc.
GRID IRON ("THE GRID"): Steel structure over the stage, just under the roof. Used to access rigging blocks.
GUTTER: The area between the first row of seats and the stage.
HEAD BLOCK: The first pulley that is directly above the counterweight carriage, arbour or winch with the principle function of changing the direction of travel of the lighting lines from vertical to horizontal.
HEMP SYSTEM: A system of hemp (now manila fibre) ropes used to raise and lower scenery.
HOUSE: The audience seating area. Also called the AUDITORIUM.
HOUSE LEFT: The area of the house to the left of the centre line, from the audience's perspective. See STAGE LEFT.
HOUSE LIGHTS: Lighting for the area where the audience sits.
HOUSE RIGHT: The area of the house to the right of the centre line, from the audience's perspective. See STAGE RIGHT.
IFR: Inherently Fire Retardant - IFR fabric is required by building codes for stage drapery
L.E.D.: Stands for Light Emitting Diode. LED technology creates light sources which are brighter and cheaper than traditional light bulbs. They are extremely efficient, give off very little heat and are light-weight, making them ideal for architectural lighting, video walls and displays.
LAMP: Refers to the complete assembly of a lighting instrument, including base, body, yoke, clamp, shuttered lenses, bulb, filament, etc.
LAVALIER: A very small microphone that is clipped onto an actor's costume, hidden in their hair/wig or affixed over their ear to provide "invisible" amplification. Often called a "LAV".
LEGS: Drapery set as masking pieces at the side of the acting area. Usually set up in matching pairs on each side of the stage and used in conjunction with borders and german masking to frame the audience's view.
LEK: Trade name for an ellipsoidal reflector spotlight.
LIGHT BRIDGE: A moveable steel structure suspended over the stage or audience area usually used for suspending lighting instruments.
LINE ARRAY: Reinforcement loudspeakers organized in vertical configuration, usually at the Proscenium line.
LINESET: Pipe batten rigged over the stage.
LOAD IN: The process of moving a show into a theatre, putting up the set, setting the lighting, etc. AKA "move-in" or "get-in".
LOAD OUT: The process of taking down and loading a show into the trucks at the end of the run. AKA "move-out" or "get-out". Also see STRIKE.
LOFT BLOCK: Pulley used in rigging systems. May be set on grid (upright rig) or loft steel (underhung rig).
LOW TRIM: The lowest point to which a piece of scenery can be flown.
MASK: To conceal the lighting instruments and stage equipment from the view of the audience, either by use of scenery or drapery.
MONOPHONIC (MONO): Single channel sound recording, as opposed to STEREOPHONIC, which uses two channels, left and right.
OFF-STAGE: Towards the unseen areas of the stage.
ON-STAGE: Towards the centre line of the stage.
ORCHESTRA: 1) Entire main floor seating area of the auditorium. 2) Circular area in Greek theatre in which the chorus performed. 3) A group of musicians including strings organized to perform ensemble music.
ORCHESTRA PIT: Sunken area immediately in front of the stage, intended to accommodate an orchestra. Also called simply the Pit.
OUT-RIGGER: Lighting pipe that extends out from the catwalk, bar or boom.
PAR CAN: A type of spotlight that provides a broad, general beam of light that covers a wide area. Par cans are light-weight, durable and easy to focus.
PIN RAIL GALLERY: Gallery above side of stage provided with belaying pins to secure temporary rigging installations from the grid, or to secure electrical cable from lighting pipes or trusses.
PIPE BATTEN: A steel pipe running parallel to the stage and to the proscenium line, rigged to motorized lift, used to support scenic, masking, or lighting elements. German Pipe batten - a pipe batten rigging perpendicular to the proscenium line, used to support masking or lighting elements.
POWERLIFT: Product name for manufacturer-specific motorized lineset.
PROPS: Short for properties. Almost anything used buy the performers that is not scenery (usually includes furniture and decorative items).
PROSCENIUM ARCH: The opening in the structural wall separating the house from the stage.
PROSCENIUM LINE: An imaginary line separating the house from the stage (uses the Proscenium Arch as reference point).
Q: See CUE
RAKE: The degree to which the stage or seating area is on an angle.
RIGGING: A general term referring to all materials (rope, wire, pulleys, blocks, etc.) required to hang any items (lights, trusses, sets, etc.) within the theatre. Also used to refer to the process of installing these items.
RIGGING STEEL: Structural steel running above the platform and audience chamber on regular centres used to support catwalks, secure loftblocks, chain motors and other rigging devices.
ROPE LOCK: A lever housed in a metal frame which activates a paw used to apply a gripping pressure on the operating line of a counterweight system.
SAFE WORKING LOAD: The maximum load that can be safely supported by a component.
SAFETY FACTOR or DESIGN FACTOR: The ratio of breaking strength to the safe working load on a line. The safety factor is determined by information on manufacturers' specifications and user evaluation of the loading situation.
SANDBAGS: Canvas bags, filled with sand and used as weights. They may also be used to weigh down jacks or used as counterweights.
SCHEDULE 40 OR 80 PIPE: Designation of 2.0" O.D. steel pipe.
SCRIM: A close-woven netting with rectangular weave. Usually hung upstage and can be made opaque or translucent depending on the position of the lights.
SHARKSTOOTH SCRIM: A netting with rectangular weave that is stronger and has a greater opacity than bobbinet. Frequently shortened to SCRIM.
SHUTTER: A device for shaping the light beam consisting of either one or two pairs of thin sliding sheets, either built into or mounted on the front of a spotlight.
SIGHTLINE: 1) The view from any seat to the stage. 2) An imaginary line extending from the most extreme side or vertical seat in the house past the proscenium arch to any position on stage to determine how much of the stage will be visible from that seating point.
SPOTLIGHT: Generic term for theatre lights.
STAGE HOUSE: The portion of a theatre containing the stage area, fly loft, grid and galleries.
STAGE LEFT: The area of the stage to the left of the centre line, from the actor's perspective.
STAGE RIGHT: The area of the stage to the right of the centre line, from the actor's perspective.
STEREOPHONIC: Double channel sound recording which uses two channels, left and right.
STRIKE: To remove all scenery and props from the stage.
T-BAR or T-BAR TRACK: Vertical metal tracks mounted against the side wall of the stage to prevent side movement of the counterweight carriage or arbour in a counterweight flying system.
TAB or TAB CURTAIN: 1) A curtain rigged to open diagonally, presenting a draped effect. 2) A piece of fabric or a flat used chiefly to mask off stage spaces.
TEASER: A horizontal border curtain. See BORDER.
TENSION GRID: A grid over the house consisting of 1/4" aircraft cable woven on 2" centres. Used in place of catwalks.
THRUST STAGE: An extension of the stage floor into the auditorium allowing the audience to be seated on three sides.
TORMENTOR: Vertical masking pieces placed just up stage and on either side of the proscenium.
TOWER: A tall light stand, or ladderlike structure, usually moveable, for mounting lighting instruments.
TRACK: 1) A metal structure with rails on which curtain runners are placed to allow curtains to open and close smoothly (noun). 2) The sideways movement of a flying piece or flown actor (verb). 3) Separate audio recording channel (noun). Most playback/recording devices have two tracks, left and right. However, for multi-track recording, they may allow four or eight tracks to be recorded onto standard media.
TRAPS: A removable section of the stage floor, which allows for access to the area under the stage floor.
TRAVELER: A slotted steel or wooden track, used to hang draw curtains.
TRUSS: A framework of metal bars and triangular cross-bracing creating a rigid structure on which to hanging lights, speakers and other equipment. Often box-shaped and called a BOX TRUSS. Commonly used for touring productions and/or where no permanent facilities are available.
UPSTAGE: Toward the rear area of the stage.
VALENCE: A horizontal masking border just downstage of the main or act curtain and usually made of the same material.
VELOUR: Any of several heavy deep pile fabrics, frequently used for main curtains.
VORTEK: Product designation for manufacturer-specific motorized lineset.
WAGON: A rolling platform, usually on casters or wheels, used for rapid scenery changes.
WINCH: A manual or power operated device used to wind cable on in order to raise and lower stage equipment.
WORKLIGHT: Light used for set-up, rehearsals or scene shifting.