1. No longer existing or living: an extinct species. See Synonyms at dead.
2. No longer burning or active: an extinct volcano.
3. No longer in use: an extinct custom.
[Middle English, from Latin exstīnctus, past participle of exstinguere, to extinguish; see EXTINGUISH.]
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.