Read the dictionary definition of adamantine. All definitions for this word.
1. impervious to pleas, persuasion, requests, reason
1. he is adamant in his refusal to change his mind
2. Cynthia was inexorable; she would have none of him
3. an intransigent conservative opposed to every liberal tendency
2. having the hardness of a diamond
3. consisting of or having the hardness of adamant