What is the definition or description of: staging?

Severity of disease: Many diseases have specific treatments based on their severity. A disease can have certain criteria to determine their severity and applying this criteria to determine how advanced the disease state is called staging. Most commonly this is applied to cancer, and be determining how far the cancer has spread locally and/or to distant sites a stage of cancer can be determined and treatment specified.

Staging: Applies to severity of medical condition, usually applied to cancer, with more advanced stages carrying poorer prognosis.