From Longman Dictionary of Contemporary EnglishPO BoxPO Box British English, P.O. Box American English /ˈpiː əʊ bɒks $ -oʊ bɑːks/ noun [countable] TCM (post office box) used before a number as an address at a post office where letters to you can be sent Write to P.O. Box 714, Key Largo, Florida.
Examples from the Corpus
PO Box• Brochures available from Glasgow 1990, PO Box 88, Glasgow.• You write to a PO box with your photo and telephone number, and they contact you if they're interested.From Longman Business DictionaryPO BoxPO Box /ˈpiː əʊ ˌbɒks◂-oʊ ˌbɑːks◂/ noun [countable] post office box; a numbered box in a post office to which someone’s mail can be sent and from which they can collect itFor further information write to PO Box 714, Key Largo, Florida. → see also box number 