The word "借光" is formed by combining the character 借, meaning "to borrow", with 光, meaning "light", directly referencing the historical practice of literally borrowing light from another person's lamp or candle for illumination. This literal meaning evolved into a metaphorical polite expression where requesting a favor or asking someone to make way is likened to borrowing light, thus forming a compound term that conveys a request for assistance or courtesy through its constituent characters.