postal order
noun🔊/ˈpəʊstl ɔːdə(r)/
🔊/ˈpəʊstl ɔːrdər/
(British English) (also money order North American English, British English)
(abbreviation PO)
an official document that you can buy at a bank or a post office and send to somebody so that they can exchange it for money （银行或邮政）汇票