The term Grassroots refers to any bottom-up, folk movement (as opposed to top-down, well-funded, corporate movement). I think the primary question to ask, to discern if a movement is grassroots or not, is, "How much influence or input can the average individual have on the project as a whole?"

If that influence or input is mostly based on how much money that person has, or who that person knows, it probably is NOT grassroots.

(Please note: This definition will change as I find out more about this.)