There are several problems with applications of the terms 'watershed' and 'stream order.' Those problems are discussed within the context of a national watershed/stream classification we believe necessary for the rational management and scientific study of streams. Although topographic watersheds can be accurately defined in most of the United States, in about 40 percent of the country it is not possible for climatic and geomorphic reasons. Hence, watersheds are not always suitable or ideal units for research and management. The authors suggest using mean annual discharge, watershed area, and mean annual discharge range instead of stream order. Those terms provide a more meaningful characterization of key physical properties and biological capacities of streams.