The Chinese word "电灯泡" (diàndēngpào), literally meaning "light bulb," is formed through a straightforward compound structure where each character contributes to the overall meaning: "电" (diàn) means "electric," "灯" (dēng) means "lamp" or "light," and "泡" (pào) means "bulb" or "bubble," together describing the object—an electric lamp bulb. Its common slang usage, referring to a third wheel who awkwardly intrudes on a couple's date, arises from a vivid metaphor: just as a bright light bulb is conspicuously present and illuminates everything, an unwanted third person makes their presence uncomfortably obvious, thus "shining a light on" the romantic couple. The term therefore operates on both a direct descriptive level and a metaphorical cultural level.