A power law fluid is a type of non-Newtonian fluid where the relationship between shear stress and deformation rate follows a power law. Some common synonyms for power law fluid include shear-thinning fluid, pseudoplastic fluid, and non-Newtonian fluid. A shear-thinning fluid refers to a fluid whose viscosity decreases as the shear rate increases, which is a characteristic of power law fluids. Pseudoplastic fluid, on the other hand, refers to a fluid whose viscosity decreases as the shear stress increases, which is also a property of power law fluids. Non-Newtonian fluid is a broader term that encompasses all fluids that do not follow the traditional linear relationship between shear stress and deformation rate.