Theatre Terms

image of question markHere you'll find over 1000 definitions of theatrical terms, from Aside, Beam Angle, and Camlock, to Upstaging, VU Meter, and Wagon.  Fully searchable, our glossary is helpful for technical staff, directors, actors, producers, or anyone wanting to better understand the inner workings of theatre.

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Term Definition Cross Reference Link
OFF BOOK or OFF-BOOK An actor or cast who has memorized their lines is said to be "off book." Often given as a reminder in a rehearsal schedule ("We will be off-book July 1.")
OFF-BROADWAY or OFF BROADWAY Said of professional theatres in New York City, not located in the traditional Broadway theatre area.
OFFSTAGE 1) Towards the nearest side of the stage from the center. (e.g. "Focus that spot offstage a bit, please") 2) The area out of sight of the audience (e.g. "Get that couch offstage!")
OHM The unit of electrical resistance.
OMNIDIRECTIONAL A type of microphone.
ON BOOK or ON-BOOK 1) To serve as prompter. 2) An actor who has not yet memorized his/her lines is said to be "on book." OFF BOOK
ONSTAGE 1) The stage area visible from the audience. Thus, an onstage chair. 2) A command from a stage manager, as in "Cast onstage!"
OPEN THE HOUSE Clearance given to Front of House staff by stage management that the stage is set and the audience can begin to take their seats. When this clearance is given, the backstage call "The House is now open, please do not cross the stage" is made.
OPEN WHITE Lighting with no color filter. Sometimes written as o/w.
OPENING Short for opening night. Opening Night
OPENING NIGHT The first performance of a production.
OPERA A dramatic composition for the stage in which all or most of the lines are sung, and typically dealing with heavily dramatic and/or tragic characters and situations.
OPERA BOUFFE A French expression for "comic opera."
OPERA BUFFA An Italian expression for "comic opera." Opera Bouffe
OPERETTA

A light dramatic entertainment with much singing and little speaking, at least in the French and Viennese tradition. Voice technique approaches that of opera, but the subject matter of the story is always light and comic. Examples include Die Fledermaus, Orpheus In the Underworld, and The Merry Widow. In the U.S., operetta took a different turn, emphasizing romance over light comedy, turning out such shows as Naughty Marietta, The New Moon, The Student Prince and Rose-Marie.

ORCHESTRA PIT A sunken area, directly in front of the forestage, usually partially screened from the audience, where instrumentalists sit to play for onstage performers.
OUT 1) In flying, means up (out of sight), as in "take out the drop." 2) In lighting, means turn off or dim completely, as in "take out the number three spot."
OUTRIGGER An extendible leg to increase the stability of access equipment, such as a "cherry picker" lift or ladder.
OVERPLAY To overact.
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