noun - The leatherback turtle or leatherback sea turtle is sometimes called the lute turtle and is the largest of all living turtles and is the fourth largest modern reptile behind three crocodilians. It is the only living species in the genus Dermochelys. It can easily be differentiated from other modern sea turtles by its lack of a bony shell. Instead, its carapace is covered by skin and oily flesh. It feeds on the common jellyfish.