obdurate

Etymology

Mid-15th century, from Latin obduratus (“hardened”), form of obdūrō (“harden”), from ob- (“against”) + dūrō (“harden, render hard”), from durus (“hard”). Compare durable, endure.

adj

1. Stubbornly persistent, generally in wrongdoing; refusing to reform or repent.
   An injury-time goal from Nikola Zigic against an obdurate Stoke side gave Birmingham back-to back Premier League wins for the first time in 14 months. February 12, 2011, Les Roopanarine, “Birmingham 1 - 0 Stoke”, in BBC
   What Tharoor dismisses as mere ‘positive by-products’ Lalvani sees as central to the India the British left behind: the botanic gardens, the forest conservancies, the Archaeological Survey of India (brainchild of the otherwise obdurate Curzon) and the free press. September 7 2017, Ferdinand Mount, “Umbrageousness”, in London Review of Books
2. (obsolete) Physically hardened, toughened.
   The past is obdurate for the same reason a turtle's shell is obdurate: because the living flesh inside is tender and defenseless. 2012, Stephen King, 11/22/63, page 827
3. Hardened against feeling; hard-hearted.

verb

1. (transitive, obsolete) To harden; to obdure.