The term MILL INPUT refers to the materials that are used to power a mill. GRIST (5 letters) is a type of GRAIN that has been ground into a coarse meal or flour. LOG (3 letters) is a large piece of wood that has been cut from a tree. LOGS (4 letters) are multiple pieces of wood that have been cut from a tree. GRAIN (5 letters) is a type of seed that is used for food, feed, or fuel. All of these materials can be used as inputs for a mill.