Meaning

noun a relatively small granular particle of a substance

noun foodstuff prepared from the starchy grains of cereal grasses

noun the side of leather from which the hair has been removed

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

Etymology from Wiktionary, CC BY-SA 3.0