A deviation in the normal structure or number of chromosomes in an organism.
A defect in a lens or mirror that prevents light rays from being focused at a single point and results in a distorted or blurred image. ◇ Aberration that results in distortion of color is called chromatic aberration. ◇ Aberration that is caused by imperfections in the surface or shape of a spherical mirror or lens is called spherical aberration. See also astigmatism, coma.2