In animals, a cuticle is a multilayered, extracellular, external body covering, usually composed of fibrous molecules such as chitin or collagen, and sometimes strengthened by the deposition of minerals such as calcium carbonate. In arthropods it is firm enough to act as a skeleton. In vertebrates, stratum corneum, which is cellular, is occasionally called cuticle.

In botany, a cuticle is a waxy layer that seals the outer surface of the epidermal cells of the leaves and stems of vascular plants, helping to retain moisture.