/ greɪn; NAmE / noun
1.
[ U , C ] the small hard seeds of food plants such as wheat , rice, etc.; a single seed of such a plant :
America's grain exports
a few grains of rice
—see also wholegrain —picture at cereal
2.
[ C ] a small hard piece of particular substances :
a grain of salt / sand / sugar
3.
[ C ] (used especially in negative sentences) a very small amount
SYN iota :
There isn't a grain of truth in those rumours.
4.
[ C ] a small unit of weight, equal to 0.00143 of a pound or 0.0648 of a gram, used for example for weighing medicines
5.
[ U ] the natural direction of lines in wood, cloth, etc. or of layers of rock; the pattern of lines that you can see :
to cut a piece of wood along / across the grain
6.
[ U , C ] how rough or smooth a surface feels :
wood of coarse / fine grain
•
IDIOMS
- be / go against the grain
••
WORD ORIGIN
Middle English (originally in the sense seed, grain of corn ): from Old French grain , from Latin granum .