Sarcopenia is a term originally coined in reference to the decline of muscle mass with aging. However, in recent times this term is being used operationally in many clinical disciplines (e.g., cancer cachexia) to define a level of muscle atrophy independent of aging per se. It is argued here that aging muscle is distinct from several other forms of muscle atrophy, particularly cancer cachexia, and therefore that use of the term sarcopenia in these non-aging contexts is unwarranted and likely to cause confusion in the field. This argument is made based upon the established histopathology of aging muscle showing it to exhibit characteristic features of muscle afflicted by repeating cycles of denervation and reinnervation. It is argued that these and other histological features should be used to distinguish sarcopenia from other clinical conditions associated with muscle atrophy and to objectively justify return of the term sarcopenia to use in the aging field exclusively. Furthermore, the histopathological features of aging muscle should be more rigorously employed to refine our search for the mechanisms of sarcopenia and its successful treatment.