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ev·o·lu·tion (ĕvə-lshən, ēvə-)
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n.
1.
a. A gradual process in which something changes into a different and usually more complex or better form.
b. A result of this process; a development: Judo is an evolution of an earlier martial art.
2. Biology
a. Change in the genetic composition of a population during successive generations, often resulting in the development of new species. The mechanisms of evolution include natural selection acting on the genetic variation among individuals, mutation, migration, and genetic drift.
b. The historical development of a related group of organisms; phylogeny.
3. Astronomy Change in the structure, chemical composition, or dynamical properties of a celestial object or system such as a planetary system, star, or galaxy. Evolution often changes the observable or measurable characteristics of the object or system.
4. A movement that is part of a set of ordered movements: naval evolutions in preparation for battle.
5. Mathematics The extraction of a root of a quantity.

[Latin ēvolūtiō, ēvolūtiōn-, from ēvolūtus, past participle of ēvolvere, to unroll; see EVOLVE.]

evo·lution·al, evo·lution·ary (-shə-nĕrē) adj.
evo·lution·ari·ly adv.

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 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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