The word "屁股" (pìgu), meaning "buttocks", is formed through a vivid conceptual combination of its two component characters. The first character, "屁", originally meaning "flatulence", hints at the associated function and location. The second, "股", means "thigh" or "share", suggesting the fleshy, rounded portion of the body. Together, they create a composite image that points directly to the rounded, lower rear part of the human torso where the thighs converge, effectively building the meaning from a functional hint and a physical description.