re·ac·tive  (r ē- ăk t ĭv)
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.
This website is best viewed in Chrome, Firefox, Microsoft Edge, or Safari. Some characters in pronunciations and etymologies cannot be displayed properly in Internet Explorer.