The word 回头 is formed through a vivid conceptual metaphor that combines two basic, concrete images: 回 (huí), meaning to turn around or return, and 头 (tóu), meaning head. It visually depicts the physical act of turning one's head around to look behind. This concrete action is then extended abstractly to represent the idea of later or in a while, as turning one's head away from the current moment implies a subsequent point in time when one will turn back to the matter at hand. Thus, the compound meaning emerges from this metaphorical blend of a physical gesture with a temporal concept.