G is for Grain

Grain is a word used to describe the direction of the fibers or layers inside a natural material like wood or stone. Materials with a grain are very easy to split along the direction of the grain, and they are naturally stronger if the grain is run lengthways along a piece of that material. Anything else that has a distinct direction in what it is made from can also be described as having a grain, such as the direction of fur on an animal's hide.