| A | B |
|---|
| Above | upstage |
| Ad lib | to extemporize during a performance |
| Amateur | one who works in the theatre without pay |
| Amber | “soft |
| Anti-climax | an event noticeably less important than preceding event |
| Apron | that part of the stage projecting in front of the curtain |
| Asbestos | fireproof curtain |
| Aside | line to audience or other character onstage |
| Backstage | portion of the theatre not included in auditorium and stage proper |
| Batten | movable pipe above the stage |
| Below | downstage of (as in "Cross below the sofa") |
| Bit part | role with very few lines |
| Blank | mental fade-out causing lines or business to be forgotten |
| Blend | actors move closer together |
| Board | diagram of theatre seating plan |
