Metaphorical analysis of tongue coating terminology and its connotation changes

The terminology and connotation changes of tongue coating are closely associated with the development of the theory of tongue inspection. Previous literature research on tongue inspection has primarily focused on tracing the origins; however, it lacks an analysis of the connotations of terminology changes. This article uses the theory of metaphorical cognition to elucidate the corresponding relationship between tongue coating terminology and its connotation changes. In the process of terminology change from "tongue fur" to "tongue moss," tongue coating has evolved from a purely pathological concept to one with physiological significance. The relationship between tongue coating and body has changed from the attachment of tongue coating to the surface of the tongue body to the inseparability of tongue coating and body. The characteristic terminology "fur" used by ZHANG Zhongjing contains architectural metaphors, reflecting the characteristic of the tongue coating being flat and slightly higher than the tongue body. During the Ming and Qing dynasties, medical practitioners gradually used the term "moss" to illustrate the organic connection between tongue coating and the tongue body through plant metaphors. They constructed metaphors of water and fire, as well as plants, to explain how tongue coating forms in both physiological and pathological states. Therefore, compared to the "fur," the "moss" has a richer metaphorical meaning, corresponding to the connotations of tongue coating terminology, which helps explain related physiological and pathological manifestations, and is a key factor affecting the evolution of tongue coating terminology.