The property of a fluid whose viscosity increases with strain or displacement.
A term from rheology; at low shear stress the initial flow of a dilatant substance is high but further increases in shear stress decrease the rate of flow. Many candy compounds exhibit dilatant behaviour. Note that dilatant behaviour may change to thixotropic behaviour by changing concentration and/or temperature.
A dilatant material is one in which viscosity increases with the rate of shear. Such a shear thickening fluid, also known by the acronym STF, is an example of a smart material, a class of materials that respond to changes in the environment.