Although the term "culture-bound syndrome" has been used for many years, a concise definition has not been available. The less precise synonym "folk illness" has implied that such syndromes exist only in other cultures. This paper provides a four-part definition to permit examination and comparison of disease categories in any system, including biomedicine. Anthropologists have tended to view biomedicine as the standard for comparison, and have not examined it in the same critical light as other systems. This may be due in part to a confusion of the biomedical classificatory system (biomedicine per se, emic level) with the biological data on which in is based (etic level). One can in fact retain use of the biological data while analyzing biomedicine, which is understood to include cultural components. Mild-to-moderate obesity in the U.S. today fits the proposed definition of a culture-bound syndrome. This paper offers a brief overview of the evidence that culture has shaped both the definition of the disease over time and its treatment.