The word "一鸣惊人" is formed through the sequential combination of four characters: 一 (one/once), 鸣 (to cry out, as a bird), 惊 (to startle), and 人 (people). It derives from an ancient story where a bird that remains silent suddenly cries out once, startling all who hear it, thus directly representing the concept of achieving startling fame or success through a single remarkable action. The characters logically connect to depict a cause-and-effect relationship where one sound leads to the astonishment of people.