a. The site of impact or explosion of a projectile, such as a missile or bomb.
b. The site of impact or explosion of a naturally falling object such as a meteoroid.
a. The site of a terrorist bombing or other violent act of destruction.
b. The site directly below, directly above, or at the point of detonation of a nuclear weapon.
3. The center of rapid or intense development or change: “The neighborhood scarcely existed five years ago, but today it is the ground zero from which designer shops and restaurants radiate” (Robert Clark).
4. The starting point or most basic level: My client didn't like my preliminary designs, so I returned to ground zero.
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.