1
- a messenger who transports goods or documents, in particular（货物或文件的）信使, 递送者, 尤指：
1.1
- a company or employee of a company that transports commercial packages and documents快递公司; 快递员：
the cheque was dispatched by courier
支票是由快递公司递送的
as modifier a courier service投递服务。
1.2
- a messenger for an underground or espionage organization（地下或间谍组织的）情报员。
2
- a person employed to guide and assist a group of tourists旅游服务员, 导游。
词源
late Middle English (denoting a person sent to run with a message)： originally from Old French coreor; later from French courier （now courrier）, from Italian corriere; based on Latin currere 'to run'.