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1. A lined and covered excavation in the ground which receives the discharge of domestic sewage or other organic wastes from a drainage system, so designed as to retain the organic matter and solids, but permitting the liquids to seep through the bottom and sides; also called a leaching cesspool or pervious cesspool.
2. (Brit.) A wooden box, usually lead-lined, constructed in a roof or gutter, to collect rainwater, which then passes to a downpipe.