terrapin \ter"rapin\, n. probably of american indian origin.
   zool.
   any one of numerous species of tortoises living in fresh and
   brackish waters. many of them are valued for food. written
   also terapin, terrapen, terrapene, turpen, and
   turapen.
   1913 webster

   note: the yellow-bellied terrapin pseudemys scabra of the
         southern united states, the red-bellied terrapin
         pseudemys rugosa or chrysemys rubriventris,
         native of the tributaries chesapeake bay called also
         potter, slider, and redfender, and the
         diamond-back or salt-marsh terrapin malaclemmys
         palustris, are the most important american species.
         the diamond-back terrapin is native of nearly the whole
         of the atlantic coast of the united states.
         1913 webster

   alligator terrapin, the snapping turtle.

   mud terrapin, any one of numerous species of american
      tortoises of the genus cinosternon.

   painted terrapin, the painted turtle. see under painted.
      

   speckled terrapin, a small fresh-water american terrapin
      chelopus guttatus having the carapace black with round
      yellow spots; -- called also spotted turtle.
      1913 webster
see also:
terapin terrapen terrapene turpen turapen pseudemys scabra 
pseudemys rugosa chrysemys rubriventris potter slider redfender 
malaclemmys palustris alligator terrapin mud terrapin cinosternon painted terrapin 
painted speckled terrapin chelopus guttatus spotted turtle