[Dave Canon]

This question always come up in the Photography Clubs set subject competitions. The usual thing to do is to fall back on the Oxford Dictionary definition and hope that it helps. We also tell the judges the same.

In this case, I actually found that the Collins Dictionary is more helpful:-

"having no reference to material objects or specific examples - not applied or practical - theoretical - hard to understand - denoting art characterised by geometric, formalised or otherwise nonrepresentational qualities"

Now doesn't that get the artistic juices flowing?