1. (

• diamond ,
• adamant

) very hard native crystalline carbon valued as a gem ;

1. (

• adamant ,
• adamantine ,
• inexorable ,
• intransigent

) 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" ;