What do we call a fluid whose viscosity remains constant regardless of the applied strain rate?

Explanation

A Newtonian fluid is characterized by a constant viscosity that does not change with the rate of deformation or strain. In contrast, viscoelastic fluids exhibit both viscous and elastic properties, pseudoplastic (shear-thinning) fluids decrease in viscosity with increased strain rate, and plastic fluids require a yield stress before they flow.