"cloaca" in the noun sense
1. cloaca
zoology) the cavity (in birds, reptiles, amphibians, most fish, and monotremes but not mammals) at the end of the digestive tract into which the intestinal, genital, and urinary tracts open
2. sewer, sewerage, cloaca
a waste pipe that carries away sewage or surface water
Source: WordNet® (An amazing lexical database of English)
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