intransigent (adj.)

• adamant
• adamantine
• ass
• cast-iron
• dissentient
• dissident
• dour
• fanatic
• firm
• flinty
• grim
• hard
• hard-core
• immovable
• immutable
• implacable
• inelastic
• inexorable
• inflexible
• iron
• irreconcilable
• maverick
• obstructive
• positivist
• relentless
• rigid
• rigorous
• rock-ribbed
• standpat
• steely
• stern
• stiff
• unaffected
• unalterable
• unbending
• unchangeable
• uncompromising
• unmoved
• unrelenting
• unyielding