PO , P.O. PO is an abbreviation for Post Office or postal order.
PO Box , P.O. Box PO Box is used before a number as a kind of address. The Post Office keeps letters addressed to the PO Box until they are collected by the person who has paid for the service.
po-faced
If you describe someone as po-faced, you think that they are being unnecessarily serious about something.
(BRIT) adj
(disapproval)
Coltrane took a rather po-faced view of this.