What term describes a performance setup where the audience views the action from one direction only?

The term that describes a performance setup where the audience views the action from one direction only is indeed the End-On or Proscenium Arch. This configuration has a stage that is framed by an arch or a proscenium, creating a distinct separation between the performers and the audience, akin to a picture frame. In this arrangement, the audience is seated directly in front of the stage, allowing for a traditional theatrical experience where the action occurs in a fixed perspective that aligns with the audience's viewpoint.

This setup is effective for various performance styles, enabling the production team to focus on visual elements such as sets and lighting, which can be designed specifically for this frontal view. It provides an intimate connection between the audience and the performance while also allowing a clear focus on the actors and the story being told.

In contrast, the other setups such as traverse, thrust, and in the round each offer different viewing experiences, often requiring the actors to engage with audiences from multiple angles or in a more immersive environment. This makes them distinct from the straightforward alignment of the End-On/Proscenium Arch format.