The word "大拇指" (dàmǔzhǐ), meaning "thumb," is formed through a descriptive compound structure in Chinese: it combines the character "大" (dà, big), the specific character for thumb "拇" (mǔ, thumb), and the general category "指" (zhǐ, finger). Literally, it translates to "the big thumb finger," where "拇" specifies the digit and "大" describes its distinguishing characteristic of relative size compared to the other fingers, all anchored under the semantic class of "指." This formation is a common logical pattern in Chinese for naming body parts, creating a clear and self-explanatory term.