The word **沉着** is a compound formed by combining two semantically related characters: **沉**, meaning "to sink" or "deep/steady," and **着**, which here functions as a suffix indicating a sustained state or manner. Together, they create a metaphorical meaning; "沉" evokes the image of something settled and unwavering, like an object resting firmly on a riverbed, while "着" extends this into a continuous quality. Thus, the compound **沉着** semantically fuses to describe the psychological state of being "calm, composed, and steady," as if one's emotions are deeply anchored and not easily disturbed.