Having a significant or powerful effect.
Usage Note: The word impactful rankles many people. Even though the -ful suffix was historically productive, yielding helpful words like eventful, bountiful, wonderful, and helpful itself, many view impactful as an affront to the English language, perhaps because of its association with the jargon of advertising and business. In our 2015 survey, 77 percent of the Usage Panel found the sentence This software will allow you to create impactful and original imagery to be unacceptable. Using this word in your speech and writing will undoubtedly have a great impact, but probably not in the way you'd like.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 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:
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.