The Collaborative International Dictionary of English v.0.48:
Bristol \Bris"tol\, n.
A seaport city in the west of England.
Bristol board, a kind of fine pasteboard, made with a
smooth but usually unglazed surface.
Bristol brick, a brick of siliceous matter used for
polishing cultery; -- originally manufactured at Bristol.
Bristol stone, rock crystal, or brilliant crystals of
quartz, found in the mountain limestone near Bristol, and
used in making ornaments, vases, etc. When polished, it is
called Bristol diamond.