A short clay pipe at the top of a chimney that helps to improve the draught. Each one exhausts a single fireplace, so several placed on top of a chimney normally implies a multi-family dwelling (or a weathy family)
up the steep and worn stairs and along a tiny passage, into a room which did not give on the street but looked out on a cobbled yard and a forest of chimney pots.
George Orwell. 1984 (1949)
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A number of chimney pots smoked over the slick tiles of the roof, adding to the general impression of greyness.