"The word for world is forest" is one of the books that is contained in the rumour that it influenced James Cameron to make his Avatar film. While I can see some similarities, there are not more in this book than there are in e.g. Fern Gulley, or Dances with Wolves (also contained in the rumour).
"The word for world is forest" introduces us to a planet with lots of forest, inhabited by a species of small creatures who call themselves the Ashthean, and who are related to humans. This species has a special way of interacting with their world, through dreams. Their peaceful life is disrupted when the humans arrive and see a lot of potential in this planet, being the trees. This is the start of an interesting number of events, where humans and Ashthean learn a lot.