English▸ noun a departure from what is normal, usual, or expected, typically an unwelcome one:
they described the outbreak of violence in the area as an aberration
I see these activities as some kind of mental aberration
[mass noun] the decade was seen as a period of aberration in the country's progress towards a democratic society.
▪ Biology a characteristic that deviates from the normal type:
colour aberrations.
▪ Optics the failure of rays to converge at one focus because of a defect 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.