/pi: ˈəʊ bɒks ||; ˈpi ˈo ˌbɑks/noun [C] a place in a post office where letters, packages, etc are kept until they are collected by the person they were sent to 邮政信箱: The address is PO Box 4287, Nairobi, Kenya. 地址是肯尼亚内罗毕4287号信箱。