numbered box in a post office where mail is delivered, box that can be rented from the post office as an alternative to having mail delivered directly to a private residence or office, call box, letter box
A post office box is a numbered box in a post office where a person's mail is kept for them until they come to collect it. = PO Box. A container, such as a pigeonhole, at a central mailing location, in which a patron's incoming mail is held until picked up by the patron. a PO Box