1. Made of or resembling adamant.
2. Having the hardness or luster of a diamond.
1. very hard; unbreakable or unyielding
2. having the lustre of a diamond
adamantine - having the hardness of a diamond
hard - resisting weight or pressure
adamantine - impervious to pleas, persuasion, requests, reason; "he is adamant in his refusal to change his mind"; "Cynthia was inexorable; she would have none of him"- W.Churchill; "an intransigent conservative opposed to every liberal tendency"