The word 阶段 is formed by combining two characters, each contributing a concrete image to create an abstract concept. The first character, 阶, originally means "steps" or "stairs", evoking the idea of ascending levels. The second, 段, means a "section" or "segment" of something longer. When merged, they metaphorically construct the concept of distinct, sequential sections within a progressive whole, like the individual steps or levels of a staircase marking different segments of a journey or process.