Meaning of GRAIN in English

grain /ɡreɪn/ BrE AmE noun

[ Date: 1200-1300 ; Language: Old French ; Origin: Latin granum 'seed' ]

1 . FOOD

a) [uncountable] the seeds of crops such as corn, wheat, or rice that are gathered for use as food, or these crops themselves:

big sacks of grain

Last year’s grain harvest was the biggest ever.

b) [countable] a single seed of corn, wheat etc:

grains of rice

2 . LINES IN WOOD ETC [singular] the natural lines you can see in a substance such as wood, which are the result of its structure

along the grain (=in the same direction as the grain)

Cut along the grain of the wood.

across the grain (=at 90 degrees to the grain)

3 . SMALL PIECE [countable] a single very small piece of a substance such as sand or salt

grain of

a grain of sand

There were crumbs and grains of sugar on the table.

4 . a grain of something a very small amount of something:

The story wouldn’t have fooled anyone with a grain of sense.

There is a grain of truth in all folklore and legend.

5 . against the grain if something goes against the grain, it is not what you would naturally or normally do:

Mary is always honest and it went against the grain to tell lies.

6 . MEASURE [countable] the smallest unit for measuring weight, equal to about 0.06 grams. It is used for weighing medicines.

⇨ take something with a pinch/grain of salt at ↑ salt 1 (3)

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.