The word "胆子" is formed through a conceptual metaphor rooted in traditional Chinese medicine and philosophy, where the physical organ, the gallbladder ("胆"), was historically believed to be the seat of courage and decisiveness. By adding the common nominal suffix "子", which often forms concrete or abstract nouns, the term transforms the literal organ into an abstract noun meaning "courage" or "nerve", directly projecting the presumed function of the bodily part onto the realm of personal spirit and boldness.