Definition of spore

• n. - One of the minute grains in flowerless plants, which are analogous to seeds, as serving to reproduce the species.
• n. - An embryo sac or embryonal vesicle in the ovules of flowering plants.
• n. - A minute grain or germ; a small, round or ovoid body, formed in certain organisms, and by germination giving rise to a new organism; as, the reproductive spores of bacteria, etc.
• n. - One of the parts formed by fission in certain Protozoa. See Spore formation, belw.