1. a small hard particle;"a grain of sand"
2. foodstuff prepared from the starchy grains of cereal grasses
3. used for pearls or diamonds: 50 mg or 1/4 carat
4. 1/60 dram; equals an avoirdupois grain or 64.799 milligrams
5. 1/7000 pound; equals a troy grain or 64.799 milligrams
6. dry seedlike fruit produced by the cereal grasses: e.g. wheat, barley, Indian corn
7. the direction or texture of fibers found in wood or leather or stone or in a woven fabric;"saw the board across the grain"