The word "上身" is a compound noun formed by combining the character "上" (shàng), meaning "upper" or "on", with "身" (shēn), meaning "body". It functions as a literal, descriptive term for the upper part of the torso or body, often referring to clothing worn on that part (like a top or blouse). Furthermore, through metaphorical extension, it has acquired a common figurative meaning in folk and spiritual contexts, where it refers to a spirit or supernatural force "attaching itself to" or "possessing" a person's body. Thus, its formation follows the common Chinese grammatical pattern of [modifier + noun] to create a new, specific concept.