The Collaborative International Dictionary
Opossum \O*pos"sum\, n. [Of N. American Indian origin.] (Zo["o]l.) Any American marsupial of the genera Didelphys and Chironectes; called also possum. The common species of the United States is Didelphys Virginiana.
Note: Several related species are found in South America. The water opossum of Brazil ( Chironectes variegatus), which has the hind feet, webbed, is provided with a marsupial pouch and with cheek pouches. It is called also yapock.
Opossum mouse. (Zo["o]l.) See Flying mouse, under Flying.
Opossum shrimp (Zo["o]l.), any schizopod crustacean of the genus Mysis and allied genera. See Schizopoda.
Wiktionary
n. (alternative spelling of yapok English)
Usage examples of "yapock".
So has the aquatic Yapock opossum of Australia, while the feet of the duck-bill are even more boldly webbed than those of the bird from which it takes its popular name.