A bound report is a document that's been physically attached together in a way that makes it a single, cohesive unit. This contrasts with unbound reports (like loose sheets of paper or pages in a folder). The binding method can vary widely, from simple staples to sophisticated techniques like spiral binding, perfect binding (like a paperback book), or case binding (like a hardcover book).
The key characteristic of a bound report is its permanence and presentation as a finished, professional product. It's often used for formal reports, dissertations, theses, proposals, and other documents where a high level of quality and organization are expected.