The word 主席 is formed by combining two characters: 主, meaning "master" or "host", and 席, meaning "mat" or "seat" (historically a place of honor at a gathering). Together, they create a conceptual compound meaning "master of the seat" or "the one who presides over the mat", visually and metaphorically evoking the person in the central, leading position at an assembly or meeting. This formation directly translates a physical position of authority into a title for a chairman or president.