against the grain; cross-grain
Woodworking term for cutting or planing against the natural direction of wood fibers, which can cause tear-out or a rough surface.
If you plane against the grain, the surface will splinter.
This board has a lot of cross-grain, making it hard to finish.
Compound of 逆 (saka, 'reverse') and 目 (me, 'grain' or 'texture'), literally 'reverse grain'.