aberration

1. In an optical system and in geometric optics, a systematic departure from an idealized path of the light rays that form an image, causing the image to be imperfect and distorted. 2. In an optical system and in physical optics, a systematic departure of a wavefront from its ideal plane or spherical form. Note: Common aberrations include spherical aberration, chromatic aberration, coma, distortion of image, curvature of field, and astigmatism. See alsochromatic aberration, distortion, field curvature, geometric optics, image, light ray, optical system, path, physical optics, wavefront.