* Common noun: This is the most general use, referring to any kind of brush, like a paintbrush, toothbrush, hairbrush, etc.
* Concrete noun: This refers to a physical object that can be touched, and a brush fits this definition.
* Count noun: It can be counted, as in "three brushes," "a dozen brushes," etc.
It's important to note that in some contexts, "brush" can be used as a verb, like "to brush your hair."