Acting glossary: cue, sides, off book, callback, beat, subtext…

Rehearsal rooms and casting emails use a vocabulary nobody explains. Sides are the audition pages, a cue is the end of the line before yours, off book means you no longer hold the script, a callback is the second audition. Below are forty terms, each defined in one or two sentences, with a link to a longer guide when we have one.

Actors · drama students · teachers · 7 min read · 40 terms

Learning and running the text

Cue. The last words, sound or action before your line, which tell you to speak. Learning lines means learning cues too. Guide: cue-based memorization.

Off book. Able to play a scene without holding the script. An “off-book date” is the rehearsal by which lines must be learned. Guide: get off book faster.

On book. Still holding the script. The person following the script to prompt actors is also said to be “on book”.

“Line!” What an actor calls in rehearsal after forgetting the text, asking the person on book for the next words without stopping the scene.

Prompt. To feed a forgotten line; also the words fed. The prompter is the person who does it, traditionally from the side of the stage.

Dry. To forget your lines mid-scene. Mostly British usage; “going up” means the same in American theatre.

Run lines. To say a scene's lines out loud, with someone reading the other parts, to check memory and cues rather than to act. Guide: run lines alone.

Italian run. A run of the lines at high speed, without acting, to test memory and pick up cues. Often done sitting down before a performance.

Paraphrase. Saying the meaning of a line in other words. Useful in early rehearsals; in performance, most scripts must be spoken exactly as written.

Scene partner. The person playing opposite you, or reading the other lines while you rehearse. Guide: AI scene partner.

Monologue. A long uninterrupted speech by one character, addressed to someone or to the audience. Auditions often ask for one or two. Guide: audition monologue practice.

Soliloquy. A speech in which a character alone on stage thinks aloud. Hamlet's “To be, or not to be” is the best-known example.

Aside. A short remark to the audience that the other characters on stage are understood not to hear.

Stage directions. The author's instructions in the script, usually in italics or brackets: entrances, actions, tone. They are not spoken. Formatting them for an app: script formatting.

Auditions

Sides. The pages of a script given to actors for an audition, usually one or two scenes rather than the whole play or screenplay. Guide: how to practice sides.

Reader. The person who reads the other character's lines opposite you in an audition. Often not an actor, so the cues arrive flat.

Cold read. Reading a script aloud with little or no time to prepare. Guide: last-minute audition.

Callback. A further audition for actors kept after the first round, often with new direction, other actors or the same sides. Guide: callback prep alone.

Self-tape. An audition you film yourself and send, following the casting team's instructions on framing, slate and sides. Guide: self-tape prep.

Slate. The short introduction at the start of an audition or self-tape: usually your name and the role, sometimes height, location or agent.

Open call. An audition open to anyone who turns up or applies, without an agent or an invitation. Also called a cattle call.

Rehearsal and staging

Table read. The cast reads the whole script aloud, seated, usually at the first rehearsal. Also called a read-through.

Blocking. The moves and positions set for each actor in each moment of a scene. Actors note them in pencil in the script.

Upstage, downstage. Upstage is away from the audience, downstage towards it. Stage left and right are the actor's left and right, facing the house.

Cheat out. To angle your body or face slightly towards the audience while still appearing to talk to another character.

Run-through. Rehearsing a whole act or the whole play without stopping, to find the shape and the stamina it needs.

Tech rehearsal. Rehearsal focused on lights, sound, scene changes and cues for the crew. Actors often stand and wait while each cue is set.

Dress rehearsal. A final run in costume and make-up, with full technical elements, played as close to performance as possible.

Understudy. An actor who learns a role in order to replace the regular performer if they cannot play.

Fourth wall. The imaginary wall between stage and audience. “Breaking the fourth wall” means speaking to or acknowledging the audience.

Ad-lib. Words improvised in performance, usually to cover a mistake, a missed entrance or a prop that has gone missing.

Acting the scene

Beat. A unit of a scene in which one thought or tactic runs, ending when it changes. In a script, “a beat” also means a short pause.

Subtext. What a character means or feels beneath the words they say. “Fine, go then” can mean “please stay”.

Objective. What a character wants from the other person in a scene or a beat. Also called intention or want; play it, not the mood.

Obstacle. Whatever stands between the character and their objective: another character, a rule, their own fear.

Given circumstances. The facts the script supplies: who, where, when, what has just happened, and the relationships. Stanislavski's term, now used everywhere.

Voice and verse

Diction. Clarity of speech: consonants, vowels and endings heard at the back of the room. Guide: tongue twisters for actors.

Projection. Making the voice carry to the whole audience with breath support rather than by shouting. Guide: voice warm-up.

Accent, dialect. An accent is how words are pronounced; a dialect adds vocabulary and grammar. Castings may ask for one. Guide: practise lines in an accent.

Iambic pentameter. The verse line Shakespeare uses most: ten syllables, five beats, stress on every second syllable, “da-DUM” five times.

Where these words meet the app

MasteringTheatre speaks the other characters' lines, so each of your lines starts on a spoken cue. After each of your lines it shows a text accuracy score: the percentage of the line's words you said as written, 90 % and above green, 70 % and above gold. It measures the text, not the acting. The prompter (Pro) shows the first words of your line after 3 to 15 seconds of silence, the app's version of calling “line!”.

This page describes the app as it was on 2026-10-06. A score measures text accuracy, not talent. Published 2026-10-06.