a. The right to purchase something before others, especially the right to purchase public land that is granted to one who has settled on that land.
b. A purchase made by such a right.
2. Prior seizure of, appropriation of, or claim to something, such as property.
3. The action of preempting, as the use of military force in a preemptive attack.
4. Law The doctrine that federal law takes precedence over state law.
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.