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re·ac·tive (rē-ăktĭv)
Share:
adj.
1. Tending to be responsive or to react to a stimulus.
2. Characterized by reaction.
3. Chemistry & Physics Tending to participate readily in reactions.
re·active·ly adv.
re·active·ness, re′ac·tivi·ty n.
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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