The word 拜拜 (bàibai) is formed through phonetic borrowing, where the sounds of the English farewell "bye-bye" are directly represented using two existing Chinese characters, 拜, which are chosen solely for their similar pronunciation. This creates a colloquial term for "goodbye" where the original meaning of the characters (which is to bow or worship) is entirely set aside, and they function purely as sound symbols. Its formation is thus a direct example of a modern loanword, reflecting cultural and linguistic exchange where a foreign expression is absorbed into everyday Mandarin speech through its audible form.