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ac·tiv·i·ty (ăk-tĭvĭ-tē)
Share:
n. pl. ac·tiv·i·ties
1. The state of being active.
2. Energetic action or movement; liveliness.
3.
a. A specified pursuit in which a person partakes.
b. An educational process or procedure intended to stimulate learning through actual experience.
4. The intensity of a radioactive source.
5. The ability to take part in a chemical reaction.
6. A physiological process: respiratory activity.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. 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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