waxy layer outside the epidermis of a leaf that retards water loss and helps protect the leaf from insects and diseases.
cuticle (Wikipedia)
A cuticle (/ˈkjuːtɪkəl/), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non-homologous, differing in their origin, structure, function, and chemical composition.