opossum \opos"sum\, n. of n. american indian origin. zool.
   any american marsupial of the genera didelphys and
   chironectes; called also possum. the common species of
   the united states is didelphys virginiana.
   1913 webster

   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.
         1913 webster

   opossum mouse. zool. see flying mouse, under flying.
      

   opossum shrimp zool., any schizopod crustacean of the
      genus mysis and allied genera. see schizopoda.
      1913 webster
see also:
didelphys chironectes possum didelphys virginiana chironectes variegatus yapock 
opossum mouse flying mouse flying opossum shrimp mysis 
schizopoda 

yapock \ya"pock\ ?; 277, n. probably from the river oyapok,
   between french guiana and brazil. zool.
   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.
   1913 webster
   1913 webster
see also:
chironectes variegatus water opossum yapack