(botany) A single male reproductive particle of which the pollen of a plant consists.

plural of pollen grain

(of timber) Having an irregular rather than a parallel grain. / (by extension) Difficult to deal with; contrary or troublesome.

plural of feed grain

plural of coarse-graining

(sciences) The rescaling of a phenomenon into units or cells of size close to the uncertainty of measurement.

Consisting of fine particles. / Having a fine, smooth texture. / (figuratively) Highly detailed.

Consisting of coarse particles. / Having a coarse, irregular texture. / (figuratively) inelegant; gross.

Grain seed saved from one year's harvest for the subsequent year's planting.

A unit of mass, equal to 1/24 of a pennyweight or 1/480 of a troy ounce, fixed at 0.064 798 91 grams under the metric system.