Abstraction indicates a departure from reality in depiction of imagery in art. This departure from accurate representation can be only slight, or it can be partial, or it can be complete. Abstraction exists along a continuum. Even art that aims for verisimilitude of the highest degree can be said to be abstract, at least theoretically, since perfect representation is likely to be exceedingly elusive. Artwork which takes liberties, altering for instance colour and form in ways that are conspicuous, can be said to be partially abstract.
Total abstraction bears no trace of any reference to anything recognisable.