Meaning of dispersive power

disper'sive pow'er

Pronunciation: [key]
— Optics. Optics.
  1. a measure of the ability of a substance to disperse light, equal to the quotient of the difference in refractive indices of the substance for two representative wavelengths divided by the difference of the refractive index for an intermediate wavelength and 1. Cf. Abbe number.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.