General:
* Framework
* Skeleton
* Structure
* Plan
* Blueprint
* Synopsis
* Summary
* Sketch
* Draft
More specific:
* Abstract (for academic papers)
* Table of contents (for books or documents)
* Roadmap (for projects or plans)
* Diagram (for visual representation)
* Chart (for visual representation)
The best word to use will depend on the specific situation.
For example, if you are talking about the structure of a story, "framework" or "skeleton" might be good choices. If you are talking about a brief summary of a topic, "synopsis" or "summary" might be more appropriate.