(noun) an electric railway operating below the surface of the ground (usually in a city )
(noun) an underground tunnel or passage enabling pedestrians to cross a road or railway
Definitions for Cloaca
(noun) (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
(noun) a waste pipe that carries away sewage or surface water