The restaurant owner was a former diplomat who often hosted international guests.

diplomat 是名词，来自法语，指"外交官"，即代表国家进行外交事务的官员。这个词由前缀diplo-（表示"双重的"）和-mat（与"人"相关）组成，暗示外交官需要处理两国之间的双重关系。