A heavyweight paper made to a calliper of .006" or higher. Used for high quality drawing and sketching pads.
Stiff, heavy paper used for business cards, programs, file folders, and inexpensive booklet covers, among other things.
Solid or laminated heavyweight paper made to a caliber thickness of .006" or higher. Bristols have a basic size of 24.5x30.5". The first pasted (laminated) papers were made in Bristol, England, by plying single sheets of paper together. Today the better bristols are true pasted sheets of two or more ply; cheaper (inferior) imitations are solid sheets labeled as "two-ply thickness".