grain

Etymology 1

From Middle English greyn, grayn, grein, from Old French grain, grein, from Latin grānum (“seed”), from Proto-Indo-European *ǵr̥h₂nóm (“grain”). Doublet of corn and gram.

noun

1. (uncountable) The harvested seeds of various grass food crops eg: wheat, corn, barley.
   We stored a thousand tons of grain for the winter.
2. (uncountable) Similar seeds from any food crop, e.g., buckwheat, amaranth, quinoa.
3. (countable) A single seed of grass food crops.
   a grain of wheat
   grains of oat
4. (countable, uncountable) The crops from which grain is harvested.
   The fields were planted with grain.
5. (uncountable) A linear texture of a material or surface.
   Cut along the grain of the wood.
   He doesn't like to shave against the grain.
6. (countable) A single particle of a substance.
   a grain of sand
   a grain of salt
7. (countable) Any of various small units of mass originally notionally based on grain's weight, variously standardized at different places and times, including
   1. The English grain of ¹⁄₅₇₆₀ troy pound or ¹⁄₇₀₀₀ pound avoirdupois, now exactly 64.79891 mg.
   2. The metric, carat, or pearl grain of ¹⁄₄ carat used for measuring precious stones and pearls, now exactly 50 mg.
   3. (historical) The French grain of ¹⁄₉₂₁₆ livre, equivalent to 53.11 mg at metricization and equal to exactly 54.25 mg from 1812–1839 as part of the mesures usuelles.
8. (countable, chiefly historical) Any of various small units of length originally notionally based on a grain's width, variously standardized at different places and times.
9. (countable, historical) The carat grain of ¹⁄₄ carat as a measure of gold purity, creating a 96-point scale between 0% and 100% purity.
10. (materials) A region within a material having a single crystal structure or direction.
11. (astronautics) The solid piece of fuel in an individual solid-fuel rocket engine.
12. A reddish dye made from the coccus insect, or kermes; hence, a red color of any tint or hue, as crimson, scarlet, etc.; sometimes used by the poets as equivalent to Tyrian purple.
    […] doing as the dyers do, who, having first dipped their silks in colours of less value, then give them the last tincture of crimson in grain. a. 1825, Quoted by Coleridge, preface to Aids to Reflection
13. The hair side of a piece of leather, or the marking on that side.
    The grain of the leather is also sometimes damaged by the filling , by the taking off the hair , and by the river work. 1773, Royal Dublin Society, The Art of Tanning and of Currying Leather
14. (in the plural) The remains of grain, etc., after brewing or distillation; hence, any residuum.
15. (botany) A rounded prominence on the back of a sepal, as in the common dock.
16. Temper; natural disposition; inclination.
17. (photography, videography) Visual texture in processed photographic film due to the presence of small particles of a metallic silver, or dye clouds, developed from silver halide that have received enough photons.

verb

1. To feed grain to.
2. (transitive) To make granular; to form into grains.
3. (intransitive) To form grains, or to assume a granular form, as the result of crystallization; to granulate.
4. To texture a surface in imitation of the grain of a substance such as wood.
5. (tanning) To remove the hair or fat from a skin.
6. (tanning) To soften leather.
7. To yield fruit.

Etymology 2

From Middle English grayn, from Old Norse grein.

noun

1. A branch of a tree; a stalk or stem of a plant.
2. A tine, prong, or fork.
   1. One of the branches of a valley or river.
   2. An iron fish spear or harpoon, with a number of points half-barbed inwardly.
      Served 5 lb of fish per man which was caught by striking with grains 4 May 1770, Stephen Forwood (gunner on H.M. Bark Endeavour), journal (quoted by Parkin (page 195)
   3. A blade of a sword, knife, etc.
3. (founding) A thin piece of metal, used in a mould to steady a core.