Intransigent
Part of speech: adjective
Definition: Unwilling to compromise or moderate a position; unreasonable; irreconcilable; stubborn.
Adamant
Part of speech: adjective
Definition: resistant to reason; determined; inflexible; unshakeable; unyielding
Part of speech: noun
Definition: a rock or mineral held by some to be of impenetrable hardness; a name given to the diamond and other substances of extreme hardnessan embodiment of impregnable hardnesslodestone; magnet