[New Latin, from Latin]: the common chamber into which the intestinal and urogenital tracts discharge especially in monotreme mammals, birds, reptiles, amphibians, and elasmobranch fishes; also: a comparable chamber of an invertebrate
Latin; akin to Greek klyzein to wash — more at clyster
First Known Use: 1599
Medical Definition of CLOACA
a: the common chamber into which the intestinal, urinary, and generative canals discharge especially in monotreme mammals, birds, reptiles, amphibians, and elasmobranch fishes b: the terminal part of the embryonic hindgut of a mammal before it divides into rectum, bladder, and genital precursors
: a passage in a bone leading to a cavity containing a sequestrum
In vertebrates, common chamber and outlet into which the intestinal, urinary, and genital tracts open. It is present in amphibians, reptiles, birds, some fishes (e.g., sharks), and monotreme mammals but is absent in placental mammals and most bony fishes. Certain animals (e.g., many reptiles and some birds, including ducks) have an accessory organ (penis) within the cloaca that is used to direct the sperm into the female's cloaca. Most birds mate by joining their cloacas in a cloacal kiss; muscular contractions transfer the sperm from the male to the female.