The word 公交 is formed by combining two existing characters: 公 (gōng), meaning "public" or "common", and 交 (jiāo), a shortened form of 交通 (jiāotōng), meaning "transportation" or "traffic". The formation conceptually blends these two ideas, where 公 specifies the nature or ownership and 交 specifies the category, creating a new, condensed term that directly signifies "public transportation". It is an example of a common Chinese word-formation process where two meaningful components are joined to efficiently convey a compound concept.