and we learn, at an early age, how to differentiate what something is from what it is not. 5 About Definitions Tree Building Shrub Dog Road Truck A tree is not a building, shrub, dog, etc. And each of the words that are crossed out could, in turn, be defined by what that word is not. The result is an endless chain of difference, but naming and categorizing difference cannot help us to understand what a word means.