- a sheet of paper, often distinctively colored or ornamented, folded vertically once to form two leaves, one of which is pasted flat to the inside of the front or back cover of a book, with the other pasted to the inside edge of the first or last page to form a flyleaf.
- either of two leaves at the front and back of a book pasted to the inside of the board covers and the first leaf of the book to secure the binding
