Source : Webster's Revised Unabridged Dictionary (1913)

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}.]



   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}.