English▸ noun a departure from what is normal, usual, or expected, typically one that is unwelcome:
they described the outbreak of violence in the area as an aberration.
▪ Biology a characteristic that deviates from the normal type:
color aberrations.
▪ Optics the failure of rays to converge at one focus because of limitations or defects in a lens or mirror.
▪ Astronomy the apparent displacement of a celestial object from its true position, caused by the relative motion of the observer and the object.