Shear-thickening is a phenomenon observed in certain materials, where their viscosity increases with the applied stress or shear rate. This means that when these materials are stirred or agitated more vigorously, they become thicker and more resistant to flow. Common examples include some types of cornstarch mixtures and non-Newtonian fluids. This behavior contrasts with shear-thinning materials, which become less viscous under stress. Shear-thickening is important in various applications, such as in body armor and protective gear, where materials need to absorb impact while remaining flexible under normal conditions.