I am doing a project on some properties of granular materials. I might have to face people who ask the definition of granular material. How can we define granular materials? One answer is "it is sand-like materials," which is true but not enough. Wikipedia gives lower limit for a material size to accept it as granular as 1 micro meteras 1 micro meter. And there is no upper limit. Is that true? What ever people are not satisfied with these definitions how should we define them?