1. plants a thin, continuous, waterproof, noncellular film secreted by epidermal and other cells on the external surface of aerial parts of vascular plants —note a cuticle tends to prevent desiccation and repels external water —see cutin, epicuticular wax 2. insects the outer noncellular layers of an insect (and other arthropod) integument secreted by the epidermis —synonym exoskeleton This definition last updated 10/25/2008