Diverse = A book about a main character who is of color, disabled, and/or LGBTQ; or a book written by an author who is of color, disabled, and/or LGBTQ.
Diverse = Set in a non-Western world or inspired by a non-Western world
One model (please note this is one definition it may not be universal)
“Nearly 90% of the books reviewed by The New York Times are written by white writers. That is not even remotely reflective of the racial makeup of this country, where 72% of the population, according to the 2010 census, is white.”
(Roxanne Gay, writer for "The Rumpus" 2012)
Studies have shown that reading fiction leads to increased empathy, which suggests that it is more important than ever to make sure books with diverse perspectives are widely available.
http://glbtrt.ala.org/rainbowbooks/“a bibliography of books with significant gay, lesbian, bisexual, or transgender content, and which are aimed at youth, birth through age 18.”