[f. ACHROMATIC + -ITY.] The quality of being achromatic; = ACHROMATISM.
1845. Encycl. Metrop., IV. 423, s.v. Light, The order in which they [lenses] are placed is of no consequence as far as Achromaticity is concerned.
1860. Sir J. Herschel, in Encycl. Brit., s.v. Telescope, This condition … furnishes the ‘equation of achromaticity’ of an eye-piece.
1876. Webb, in Chambers’ Astron., 745. Errors due to the imperfect achromaticity of the object-glass.
