The word **邮差 (yóuchāi)**, meaning "mail carrier" or "postman," is a compound noun formed through semantic combination. The first character, **邮 (yóu)**, means "mail" or "postal," relating directly to the function. The second character, **差 (chāi)**, in this context is a classical term for "messenger," "errand runner," or "someone dispatched on official duty." Historically, **差** referred to a person assigned a task by an authority. Therefore, **邮差** literally translates to "postal dispatch-person" or "one dispatched for mail," efficiently describing the occupation as a person sent to deliver correspondence.