n.

1. （書的）一張；（單面標頁碼之書的）一頁；頁碼[C]
   The manuscript you sent us has a folio missing.

   你送來的原稿少了一頁。

2. 對開紙（將全紙對摺而成）；對開本[U]
3. 對開本的書（最大開本）[C]
   a Shakespeare folio

   一部對開本的莎士比亞作品

a.

1. 對開的；對開本的

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.