noun

• (strictly) Writing paper sheets measuring 13.25 x 16.5 inches
• (more usually) Such a sheet folded or cut in half, thus approximately 8 x 13.25 inches.
• Printing paper measuring 13.5 inches x 17 inches.
• Alternative form of fool's cap [A cap, usually brightly coloured with bells and tassels, as worn by a court jester or fool.]