Here's why:
* Abstract nouns represent concepts, ideas, qualities, or states of being. They are things you cannot touch or see physically.
* "Abstract" itself refers to the quality of being abstract.
Let's look at an example:
* Concrete noun: The chair is comfortable. (You can physically touch a chair)
* Abstract noun: The comfort of the chair is undeniable. (Comfort is an idea or feeling)
So, "abstract" itself is a noun that describes the concept of being abstract.