Aberration refers to wandering away. such as –
(1) Used of light when a lens does not bring all the light (e.g. of different colors) to the same point is called Chromatic Aberration. or
Where the lens is not correctly curved and so bends part of the picture out of shape is called Spherical Aberration.
(2) When a man on the Earth is looking at a star, he does not see the star where it really is. Because, the star-light takes some time to reach him and the Earth is moving. So he sees the star where it was.
That is to say, the difference between the seeming and the real place is called the Aberration.
Reference: An Elementary Scientific and Technical Dictionary
What is Aberration?