The word "六腑" is formed by combining the character "六", meaning "six", with the character "腑", which refers to the hollow organs in traditional Chinese medicine. Specifically, "腑" denotes a category of organs, and when prefixed with "六", it specifies the set of six hollow organs: the gallbladder, stomach, small intestine, large intestine, bladder, and triple burner. Thus, the term directly indicates a countable group of anatomical entities through this numeral-noun construction.