break (thing)

What a putt does on a green. Reading the break is one of the fine arts of golf. The type of grass you are putting on makes a great deal of difference. Bent grass has very little grain, so you can pretty well trust your eyes. Bermuda Grass has a lot of grain, so this requires a lot of practice to know if you are "into the grain" or "downgrain." It can make a huge difference in how hard you need to hit the putt.