grain -- (a relatively small granular particle of a substance; "a grain of sand"; "a grain of sugar")
grain, food grain, cereal -- (foodstuff prepared from the starchy grains of cereal grasses)
grain -- (the side of leather from which the hair has been removed)
grain, metric grain -- (a weight unit used for pearls or diamonds: 50 mg or 1/4 carat)
grain -- (1/60 dram; equals an avoirdupois grain or 64.799 milligrams)
grain -- (1/7000 pound; equals a troy grain or 64.799 milligrams)
grain, caryopsis -- (dry seed-like fruit produced by the cereal grasses: e.g. wheat, barley, Indian corn)
grain -- (a cereal grass; "wheat is a grain that is grown in Kansas")
grain -- (the smallest possible unit of anything; "there was a grain of truth in what he said"; "he does not have a grain of sense")
grain -- (the direction, texture, or pattern of fibers found in wood or leather or stone or in a woven fabric; "saw the board across the grain")
texture, grain -- (the physical composition of something (especially with respect to the size and shape of the small constituents of a substance); "breadfruit has the same texture as bread"; "sand of a fine grain"; "fish with a delicate flavor and texture"; "a stone of coarse grain")
Overview of verb grain
The verb grain has 4 senses
ingrain, grain -- (thoroughly work in; "His hands were grained with dirt")
grain -- (paint (a surface) to make it look like stone or wood)