English definition of “grain”
SEED [C, U] › a seed or seeds from types of grass which are eaten as food: grains of wheat/rice
PIECE [C] › a very small piece of something: a grain of sand/sugar
QUALITY [no plural] › a very small amount of a quality: There isn't a grain of truth in her story.
the grain › the natural direction and pattern of lines which you can see in wood or material: to cut something along/against the grain → See also take sth with a pinch of salt