Scope Definition

One of the first and most important steps in project management is to flesh out a statement or scope definition which identifies and describes all work necessary to produce the final product. The statement establishes the tone for the remainder of the planning efforts and therefore should be sufficiently detailed. Keep in mind however that being too detailed can be as bothersome as not providing enough detail.
During the planning phase the project management team should identify and describe all work that is necessary to bring the project to fruition. The scope definition is meant to ensure that everyone on the team understands what is expected of them during the project. In addition all project work that can be reasonably predicted must be ascertained and reported. The scope definition should also allow for appropriate administrative control during the project management process.
Suitable scope definition is essential to the success of the project and should be given ample consideration and thought. If this step is skipped or inadequately developed it will most likely mean that additional project planning will suffer as a result.

This term is defined in the 3rd edition of the PMBOK but not in the 4th