noun

1. a departure from what is right, true, correct, etc.
2. a deviation from the normal or the typical
3. mental derangement or lapse
4. Astron. a small, periodic apparent change in the observed position of a celestial object, caused by the constantly changing position of the earth and the finite speed of the object's light
5. Optics
   1. the failure of light rays from one point to converge at a single focus
   2. a fault in a lens or mirror causing such failure

Etymology: L abberatio < aberrare: see aberrant