1. A violent jarring; a shock: The concussion from the explosion broke windows three blocks away.
2. An injury to an organ, especially the brain, produced by a violent blow and followed by a temporary or prolonged loss of function.
[Middle English concussioun, bruise, contusion, from Latin concussiō, concussiōn-, concussion, from concussus, past participle of concutere, to strike together; see CONCUSS.]
con·cussive (-kŭsĭv) adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 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.