adamant

Etymology

From Middle English adamant, adamaunt, from Latin adamantem, accusative singular form of adamās (“hard as steel”), from Ancient Greek ἀδάμας (adámas, “invincible”), from ἀ- (a-, “not”) + δαμάζω (damázō, “I tame”) or of Semitic origin.

adj

1. (said of people and their conviction) Firm; unshakeable; unyielding; determined.
   Broiles and Kirkley were adamant about getting out of the lawsuit, but Mike and Dee were equally adamant about not wanting to sign a letter of apology 2002, Charles Moncrief, Wildcatters: The True Story of how Conspiracy, Greed and the IRS ..., page 195
   Johan is determined to play the field and adamant about never committing. 2006, Cara E. C. Vermaak, Confessions of the Dyslexic Virgin, page 275
   What good would such foolishness do a mountain man? But Pa had been adamant. Just as he'd been adamant about their reading, writing, numbers, geography, and languages. Just as he'd been adamant about using proper grammar 2010, Deeanne Gist, Maid to Match, page 94
2. (of an object) Very difficult to break, pierce, or cut.
   Unprotected matter, however adamant, would have been ground to dust ages ago. 1956, Arthur C. Clarke, The City and the Stars, page 34

noun

1. An imaginary rock or mineral of impenetrable hardness; a name given to the diamond and other substances of extreme hardness.
   This then is and alwayes hath ben the fashion of Worldlinges, & reprobate persons, to harden their hartes as an adamant stone, against anye thinge that shalbe tolde the for amendement of their lives, and for the savinge of their soules. 1582, Robert Parsons, chapter 8, in The first booke of the Christian exercise, appertayning to resolution, G. Flinton
   As an adamant harder than flint have I made thy forehead … 1611, King James Translators, Ezekiel 3:9
2. An embodiment of impregnable hardness.
   Actual life might seem to her so real that she could not detect the union of shadow and adamant that men call poetry. 1907, E.M. Forster, The Longest Journey, Part I, XV [Uniform ed., p. 163]
3. (archaic) A lodestone.
4. (obsolete or historical) A substance that neutralizes lodestones.
   An Adamant hinders the attractive vertue, as also Garlick rubbed on the Magnet; for its attractive faculty is not so valid, but it may be easily deluded, obscured, and superated […] 1657 [1608], Jean de Renou, translated by Richard Tomlinson, A Medicinal Dispensatory[…], page 418
   But we know from book 37 of the Natural History that adamant works on magnets in exactly the same way that garlic does: robbing them of their power to attract. 2012, Daryn Lehoux, What Did the Romans Knows? An Inquiry into Science and Worldmaking, page 139