A nib is the part of a quill, dip pen or fountain pen which comes into contact with the writing surface in order to deposit ink. Different types of nibs vary in their purpose, shape and size, as well as the material from which they are made.
You already know what an art brush looks like!
For $5, I will draw any subject you want (a scene, a character, etc) for your project. I'll deliver it inked.