iamb -- a metrical unit of two syllables, the first unstressed, the second stressed: the regular rhythm of blank verse rather like the beating of your heart - buh boom, buh boom, buh boom.
iambic pentameter -- a ten syllable line of verse with five stresses - di dum, di dum, di dum, di dum, di dum.
illusion of the first time -- a spontaneous quality of response as if this were the first time this situation had occurred
imagery -- the use of emotionally charged words and phrases that conjure up vivid mental pictures on the imagination.
impersonate -- to play a role on stage usually of a well known person
impresario -- a producer and promoter of musical shows such as opera
impressionism -- an early 20th century movement in which the impressions of a author were predominant in a play rather than any realistic portrayal of life
improvisation -- scene that is created and performed spontaneously by actors who make up their own dialogue and actions.
improvise -- to ad lib or invent dialogue not in the script
incidental music -- played during a dramatic performance
inciting incident -- incident near the beginning of a play that gets the main action started
industrial felt -- a specialty fabric used to make hats, props, and, sometimes, scenery; looks like felt, but much heavier
inflection -- the rise and fall of the voice from one pitch level to another.
ingenue -- role of a young girl
in medias res -- literally "in the middle of things" - when a scene or the play itself begins in the middle of things, before the plot has been laid out.
inner stile -- vertical toggles or framing in a flat which determines the width of the window or door opening
in-ones -- the first set of legs behind the proscenium arch; also used to describe scenes that are played in front of a drop placed just behind the first set of legs
intensity -- measured in lux, lumens and foot-candles. For any given luminaire (lighting instrument or fixture), this depends upon the power of the lamp, the design of the instrument (and its corresponding efficiency), the presence or absence of colour gels or gobos, distance from the area to be lit and the beam or field angle of the fixture, the colour and substance to be lit, and the neuro-optics of the total scene (that is, the relative contrasts to other regions of illumination).
intention -- what the character really feels and thinks, not just the literal meaning of the dialogue; an actor's purpose for being in a scene.
intermission -- intervals between the acts or scenes allowing for set changes audience respite, costume change, etc.
investor -- (angel) financial backer for a commercial production. Because of the high cost of mounting a commercial production ($2 million for a “straight” play and $5 million to $8 million for a musical), producers look to corporate funding rather than to individual investors.
iris -- the control on a follow spot that makes the circle of light bigger or smaller
irising -- on a follow spot, making the circle of light smaller (in) or larger (out)
irony -- verbal irony: saying one thing but meaning another; dramatic irony: the audience knows something that a character does not.
iterative imagery -- repeated imagery, images which recur throughout the play.