word-forming element meaning "small in size or extent, microscopic; magnifying;" in science indicating a unit one millionth of the unit it is prefixed to; from Latinized form of mikros, Attic form of Greek smikros "small, little, petty, trivial, slight," perhaps from PIE *smika, from root *smik- "small" (source also of Old High German smahi "littleness"), but Beekes thinks it a Pre-Greek word.
"reproductive body in flowerless plants corresponding to the seeds of flowering ones," 1836, from Modern Latin spora, from Greek spora "a seed, a sowing, seed-time," related to sporas "scattered, dispersed," sporos "a sowing," from PIE *spor-, variant of root *sper- "to spread, sow" (see sparse).
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Harper, D. (n.d.). Etymology of microspore. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/microspore