Tegument /ˈtɛɡjʊmənt/ is a term in helminthology for the outer body covering of members of the phylum Platyhelminthes. The name is derived from a Latin word tegumentum or tegere, meaning "to cover".[1][2] It is characteristic of flatworms including the broad groups of tapeworms and flukes. Once considered to be a non-living component, it is now known to be a dynamic cellular structure. In fact it is a living structure consisting of proteins, lipids, carbohydrates and RNA. It forms the protective layer and the host-parasite interface of the worms, serving both secretory and absorptive functions.[3]