noun
reply-paid postcard; postcard with a reply card attached
A postcard consisting of two connected cards: one for the sender's message and one for the recipient's reply, with return postage prepaid.
結婚式の出欠を確認するために往復はがきを送った。
I sent a reply-paid postcard to confirm attendance at the wedding.
往復
On the reply side of a reply-paid postcard, you write your own address in advance.