Aberration

{ab-er-a’ -shun) [ab, from; errare, to wander]. Deviation from the normal; mental derangement; fetal malformation; vicarious menstruation; escape of the fluids of the body by an unnatural channel. In optics, any imperfection of focalization or refraction of a lens. A., Chromatic, the dispersion arising from unequal refraction of light of different parts of the spectrum. The violet rays, being more refrangible than the red rays, are brought to a focus nearer the lens, and the image is surrounded by a halo of colors. A., Mental, a degree of paranoia that may or may not amount to insanity. A., Spheric, the exce of refraction of the peripheral part of a convex lens over the central part, producing an imperfect focus and a blurred image. 20