黏弹性（英语：Viscoelasticity）是黏性和弹性的结合，亦即黏性流体与弹性固体的流动特性组合，日常生活中，水的流动就是典型的黏性流体，橡胶的变形属于弹性体。

Viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Viscous materials, like honey, resist shear flow and strain linearly with time when a stress is applied. Elastic materials strain when stretched and quickly return to their original state once the stress is removed. Viscoelastic materials have elements of both of these properties and, as such, exhibit time-dependent strain. Whereas elasticity is usually the result of bond stretching along crystallographic planes in an ordered solid, viscosity is the result of the diffusion of atoms or molecules inside an amorphous material.