The Collaborative International Dictionary
Yapock \Ya"pock\ (?; 277), n. [Probably from the river Oyapok, between French Guiana and Brazil.] (Zo["o]l.) A South American aquatic opossum ( Chironectes variegatus) found in Guiana and Brazil. Its hind feet are webbed, and its fore feet do not have an opposable thumb for climbing. Called also water opossum. [Written also yapack.]
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.