aberration (ab-er-a's hun). 1

Any deviation from the normal course. 2. In optics, the deviation of the rays of light from the principal focus of a curved lens or speculum. 3.See mental a. 4. An abnormal determination of one of the fluids of the body, especially the blood, to a part, as in vicarious menstruation; a metastasis, chromatic a. In the refraction of light by a lens, an inequality in the degree of refraction of the rays of the different colors, so that a series of tinted images is produced more or le removed from the focus, mental a. A vague term signifying strange or abnormal mental functioning; in law used loosely as synonymous with the still more vague term insanity. spherical a. In the refraction of light by a lens, an inequality in the degree of 3 convergence of the rays from different portions of the lens, producing a series of images at different focal distances, so called because the character of the a. is due to the fact that the surface of the lens is a segment of a sphere. [Lat., aberratio^ a deviation.]