ad·a·mant (ădə-mənt, -mănt′)
Not willing to change one's opinion, purpose, or principles; unyielding.
1. A stone once believed to be impenetrable in its hardness.
2. An extremely hard substance.
[From Middle English, a hard precious stone, from Old French adamaunt, from Latin adamās, adamant-, from Greek, unconquerable, hard steel, diamond; see demə- in the Appendix of Indo-European roots.]
ada·mance, ada·man·cy 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.