Frindle

Frindle by Andrew Clements is a 112 page book about Nick Allen, who creates a new word. He pursued it through news reporters, the obnoxious elderly, and sentence after sentence of the same thing: I am writing this sentence with a pen. Every so often, though, everyone would write "I am writing this sentence with a frindle. 
He was neither a good student not a bad student, just a creative boy who (almost) always manages to ask questions that put off daily homework. Frindle is the story of a question so good that a war between teachers and students begin. 
Can YOU figure out what the word "frindle" means???????