1. Impervious to pleas, persuasion, requests, reason
   "he is adamant in his refusal to change his mind";
   - adamantine, inexorable, intransigent, unbudgeable

1. Very hard native crystalline carbon valued as a gem
   "The engagement ring featured a brilliant adamant in a platinum setting";
   - diamond

Derived forms: adamants

See also: inflexible

Type of: atomic number 6, C, carbon, transparent gem

Encyclopedia: Adamant, Vermont