spore

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A small, usually single-celled reproductive body that is highly resistant to desiccation and heat and is capable of growing into a new organism, produced especially by certain bacteria, fungi, algae, and nonflowering plants.
2. n. A dormant nonreproductive body formed by certain bacteria in response to adverse environmental conditions.
3. v. To produce spores.

Century Dictionary and Cyclopedia

1. n. A. Middle English form of spur.
2. n. In botany, a single cell which becomes free and is capable of developing directly into a new morphologically and physiologically independent individual. The name is given to all the reproductive bodies of cryptogamous plants, which are the analogues of the seeds of the higher or flowering plants, from which they further differ by having no embryo. In the majority of cases a spore consists of a nucleated mass of protoplasm, inclosing starch or oil as reserve nutritive material, surrounded by a cellwall. In those cases in which the spore is capable of germination immediately on the completion of its development, the cell-wall is a single delicate membrane consisting of cellulose; but in those cases in which the spore must pass through a period of quiescence before germination, the wall is thick and may consist of two layers, an inner, the endospore, which is delicate and consists of cellulose, and an outer, the exo spore, which is thick and rigid, frequently dark-colored, and beset externally with spines or bosses, and which consists of cutin. In certain plants, as some algæ and fungi, spores are produced which are for a time destitute of any cell-wall. They are further peculiar in that they are motile, on which account they are called zoöspores. In the various divisions of cryptogams the spores are produced in many different ways and under various conditions. See æcidiospore, ascospore, bispore, carpospore, chlamydospore, clinospore, macrospore. microspore, oöspore, protospore, pseudospore, pycnidiospore, stylospore, teleutospore, tetraspore, uredospore, zoöspore, zygospore, etc.
3. n. In zoology, the seed or germ of an organism, of minute size, and not of the morphological value of a cell, such as one of the microscopic bodies into which the substance of many protozoans is resolved in the process of reproduction by sporation; a sporule; a gemmule, as of a sponge.
4. n. In biology, an organic body of extremely minute size, and not subject to ordinary classification; a sporozoid or zoöspore; a living germ, as a seed of certain diseases.
5. n. Figuratively, a germ; a seed; a source of being.

Wiktionary

1. n. A reproductive particle, usually a single cell, released by a fungus, alga, or plant that may germinate into another.
2. n. A thick resistant particle produced by a bacterium or protist to survive in harsh or unfavorable conditions.
3. v. To produce spores.

GNU Webster's 1913

1. n. One of the minute grains in flowerless plants, which are analogous to seeds, as serving to reproduce the species.
2. n. An embryo sac or embryonal vesicle in the ovules of flowering plants.
3. 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
4. n. One of the parts formed by fission in certain Protozoa. See Spore formation, belw.

WordNet 3.0

1. n. a small usually single-celled asexual reproductive body produced by many nonflowering plants and fungi and some bacteria and protozoans and that are capable of developing into a new individual without sexual fusion