The term POST OFF is a combination of two words, 'POST' and 'OFF'. POST refers to the delivery of mail or parcels, while OFF refers to the act of sending something away. The crossword solution for this term is REMIT, which means to send money or payment. This could refer to sending money through the mail, such as a check or money order, or it could refer to paying a bill online. In either case, remitting money is an important part of the POST office's job.