Did you ever try to define "abstract"? Or look it up on google? Let's just say it's not an easy subject to define:) After going through quite a few "double Dutch" words and phrases, I found one that is pretty comprehendible:
"An abstract aims to present only the gist of the subject matter"Which in photography pretty much means that you show only a part of the bigger object, like just a part of a building or just the texture of a door. It can be a pattern found in any object, big or smal, industrial or natural. Abstracts are often easy on the eye, easy to like, but it takes a practiced and creative eye to spot a good motive. An abstract motive can be found EVERYWHERE, you just have to open your mind to them:) Good luck!!