aberration

(ăbˌə-rāˈshən)

1. A deviation from the proper or expected course. See Synonyms at deviation.
2. A departure from the normal or typical: events that were aberrations from the norm.
3. Psychology A disorder or abnormal alteration in one's mental state.
4. a. A defect of focus, such as blurring in an image.
   b. An imperfect image caused by a physical defect in an optical element, as in a lens.
5. The apparent displacement of the position of a celestial body in the direction of motion of an observer on Earth, caused by the motion of Earth and the finite velocity of light.
6. Genetics A deviation in the normal structure or number of chromosomes in an organism.

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aberration

top: spherical aberration

bottom: chromatic aberration