The formation of the word 坐下 is a direct and intuitive conceptual fusion: the first character 坐 depicts a person sitting on the earth (from its ancient pictographic origins), representing the state or action of sitting, while the second character 下 means "downward". When combined, they sequentially and seamlessly merge the two ideas into a single, fluid motion, the act of lowering oneself to transition into a seated position. It is not merely two separate concepts placed side-by-side, but a compound that visually and notionally encapsulates the complete action from start to finish.