aberration

(ab-er-a’shun) [L. ab from + err a're to wander]. 1. Deviation from the usual course. 2. A disordered state of the intellect. 3. Imper- " fect refraction or focalization in a lens. | chromatic a., an unequal refraction of differently colored rays, producing a blurred image. dioptric a. Same as spheric a. distantial a., a blurring of vision due to distance. lateral a., deviation of a ray from the focus measured upon a line perpendicular to the axis at the focus. longitudinal a., deviation of a ray from the focus measured on the axis. mental a., unsoundne of mind, especially one that is not sufficient to constitute insanity. meridional a., the variation of refractive power in different portions of the same meridian of a lens. newton i an a. Same as chromatic a. spheric a., the imperfect focalization of a convex lens, due to the fact that the rays from the periphery come to a focus sooner than the others.