adamantyoudaoicibaDictYouDict[adamant 词源字典]
adamant: [14] In Greek, adamas meant ‘unbreakable, invincible’. It was formed from the verb daman ‘subdue, break down’ (which came from the same source as English tame) plus the negative prefix a-. It developed a noun usage as a ‘hard substance’, specifically ‘diamond’ or ‘very hard metal’, and this passed into Latin as adamāns, or, in its stem form, adamant-. Hence Old French adamaunt, and eventually English adamant.
=> diamond, tame[adamant etymology, adamant origin, 英语词源]
adamant (adj.)youdaoicibaDictYouDict
late 14c., "hard, unbreakable," from adamant (n.). Figurative sense of "unshakeable" first recorded 1670s. Related: Adamantly; adamance.
adamant (n.)youdaoicibaDictYouDict
mid-14c., from Old French adamant and directly from Latin adamantem (nominative adamas) "adamant, hardest iron, steel," also figuratively, of character, from Greek adamas (genitive adamantos) "unbreakable, inflexible" metaphoric of anything unalterable, also the name of a hypothetical hardest material, perhaps literally "invincible," from a- "not" + daman "to conquer, to tame" (see tame (adj.)), or else a word of foreign origin altered to conform to Greek.

Applied in antiquity to a metal resembling gold (Plato), white sapphire, magnet (by Ovid, perhaps via confusion with Latin adamare "to love passionately"), steel, emery stone, and especially diamond (see diamond). "The name has thus always been of indefinite and fluctuating sense" [Century Dictionary]. The word was in Old English as aðamans "a very hard stone."