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postcard
memo; note; card
お礼の羽書を書いた。
I wrote a thank-you postcard.
年賀の羽書を百枚も印刷した。
I printed as many as a hundred New Year's postcards.
羽書が届くまでに三日くらいかかるらしいよ。
I hear it takes about three days for a postcard to arrive.