The Chinese word **便当** (biàndang) for "packed meal" or "lunchbox" is a direct loanword from the Japanese **弁当** (bentō), which itself originates from a Chinese historical term meaning "convenient." The formation is a process of *re-borrowing*: the Chinese characters 便 (biàn, "convenient") and 当 (dāng, "appropriate" or "to serve a function") were originally used in classical Chinese. This compound was adopted into Japanese to describe a convenient, portable meal. In the late 20th century, primarily through cultural exchange via Taiwanese Mandarin, the term was re-introduced into modern Chinese usage, carrying the specific Japanese meaning. Thus, its formation is not based on native Chinese word-creation rules for this meaning, but on semantic borrowing, where the existing characters are used to represent a foreign concept phonetically and ideographically.