a. Extremely persistent in adhering to or doing something; stubborn or relentless: "tenacious defenders of their harsh and pitiless land" (Dee Brown).
b. Characterized by extreme persistence; relentless or enduring: tenacious detective work; tenacious superstitions.
2. Holding together firmly; cohesive: a tenacious material.
3. Clinging to another object or surface; adhesive: tenacious lint.
4. Tending to retain; retentive: a tenacious memory.
[From Latin tenāx, tenāc-, holding fast, from tenēre, to hold; see ten- in the Appendix of Indo-European roots.]
te·naci·ty (tə-năsĭ-tē), te·nacious·ness n.
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.