1 a [noncount] : the seeds of plants (such as wheat, corn, and rice) that are used for food
▪ bread made from whole wheat grain ▪ The machine grinds grain into flour. ; also [count] : a single seed of wheat, corn, rice, etc.
▪ a grain of rice
b : a plant that produces grain [count] ▪ The farm grows a variety of grains. [noncount] ▪ fields planted with grain 2 [count] a : a small, hard piece of something
▪ a grain of sand/salt — see also take (something) with a grain of salt at ¹salt
b : a very small amount of something
▪ Anyone with a grain of sense knows that she's lying. ▪ There is not a grain of truth in what he said. 3 [count] a : the way the lines or fibers in something (such as wood) are arranged — usually singular ▪ She sanded the wood in the direction of the grain.
b : the way that the surface of something feels when it is touched — usually singular ▪ The wood has a fine/coarse grain. 4 [count] : a unit of weight equal to 0.0648 grams