To forget or skip lines

• uncover lines

• drop lines

• proceed over lines

The reason a character does something

• apples

• influence

• motivation

Line of one character which immediately precedes the lines of the next character

• cast line

• cue line

• course line

To improvise a conversation or scene - no script

• improv or improvisation

• drop lines

• ask for help

Something that is standing in the way of the goal of a character

• obstacle

• strategy

• blocking

Action performed on stage by an actor; this is what you do on stage

• onstage shenanigans

• stage happenings

• stage business

Providing a forgotten line

• giving lines

• prompting

• dropping lines

Not on the visible stage

• onstage

• set

• offstage

Waiting for the audience to finish laughing

• holding for silence

• holding for a blackout

• holding for a laugh

Movement of a character from one location to another

• cross

• blocking

• cheating out