Source : Webster's Revised Unabridged Dictionary (1913)

Leatherback \Leath"er*back`\, n. (Zo["o]l.)
   A large sea turtle ({Sphargis coriacea}), having no bony
   shell on its back. It is common in the warm and temperate
   parts of the Atlantic, and sometimes weighs over a thousand
   pounds; -- called also {leather turtle}, {leathery turtle},
   {leather-backed tortoise}, etc.

Source : WordNet®

leathery turtle
     n : wide ranging marine turtle with flexible leathery carapace;
         largest living turtle [syn: {leatherback turtle}, {leatherback},
          {Dermochelys coriacea}]