endpaper

詳細解釋：

endpaper 也作 end paper

n.（名詞）
Either of two folded sheets of heavy paper having one half pasted to the inside front or back cover of a book and the other half pasted to the base of the first or last page.Also called end leaf
蝴蝶頁，襯頁：兩張疊起來的加厚紙的任一頁，其中一頁與書的封面或封底的里板粘在一起，另一頁粘到首頁或底頁的底部也作 end leaf