What term describes an actor's movement that occurs without the audience's knowledge?

The term that describes an actor's movement that occurs without the audience's knowledge is "cheat." In the context of theatre, cheating usually refers to the technique of positioning an actor in such a way that their actions are made visible to the audience without being overtly noticeable. This can involve subtle movements or adjustments that allow for better sight lines or engagement with the audience while maintaining the illusion of the scene.

While other options, such as "stealth," might imply a hidden or secret movement, they are not specific to theatrical terminology or practice. "Crossfade" refers to a lighting change rather than an actor's movement, and "sneak" implies a more overt action of moving quietly, which doesn’t align with the nuanced nature of the term "cheat" within theatrical performance. This makes "cheat" the most appropriate and accurate term in this context.