The term 'Unit of Refractive Power' can be summarized as the dioptre, which is a unit of measurement for the refractive power of a lens or curved mirror. It is used to measure the optical power of a lens, and is equal to the reciprocal of the focal length in metres. The dioptre is an important unit of measurement in optics, and is used to calculate the power of lenses used in eyeglasses, contact lenses, and other optical devices.