n.

1. （书的）一张；（单面标页码之书的）一页；页码[C]
   The manuscript you sent us has a folio missing.

   你送来的原稿少了一页。

2. 对开纸（将全纸对折而成）；对开本[U]
3. 对开本的书（最大开本）[C]
   a Shakespeare folio

   一部对开本的莎士比亚作品

a.

1. 对开的；对开本的

n.

1. a sheet of paper folded once to form two leaves (four pages) of a book.
   ▸a book made up of such sheets.
2. an individual leaf of paper or parchment numbered on the recto or front side only.
   ▸the page number in a printed book.