The word 搭乘 is a formal compound verb formed by combining two synonymous characters, 搭 (dā) and 乘 (chéng), both of which individually mean "to ride" or "to board" a vehicle. This type of construction, where two characters with similar meanings are paired, is common in Chinese to create a more precise or formal term; here, it specifically and politely refers to the act of taking a mode of transport, such as a bus, train, plane, or taxi. The combined word emphasizes the action of boarding and riding, and it is more standard and written in register than using either character alone in many contexts.