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spe·cies (spēshēz, -sēz)
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n. pl. species
1. Biology A group of closely related organisms that are very similar to each other and are usually capable of interbreeding and producing fertile offspring. The species is the fundamental category of taxonomic classification, ranking below a genus or subgenus. Species names are represented in binomial nomenclature by an uncapitalized Latin adjective or noun following a capitalized genus name, as in Ananas comosus, the pineapple, and Equus caballus, the horse.
2. Logic A class of individuals or objects grouped by virtue of their common attributes and assigned a common name; a division subordinate to a genus.
3. Chemistry A set of atoms, molecules, ions, or other chemical entities that possess the same distinct characteristics with respect to a chemical process or measurement.
4. A kind, variety, or type: "No species of performing artist is as self-critical as a dancer" (Susan Sontag).
5. Roman Catholic Church
a. The outward appearance or form of the Eucharistic elements that is retained after their consecration.
b. Either of the consecrated elements of the Eucharist.

[Middle English, logical classification, from Latin speciēs, a seeing, kind, form; see spek- in the Appendix of Indo-European roots.]

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
 

Indo-European & Semitic Roots Appendices

    Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

    Indo-European Roots

    Semitic Roots

    The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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