Mid-15th century, from Latin obduratus, form of obdūrō ("harden"), from ob- ("against") + dūrō ("harden, render hard"), from durus ("hard").

• (RP) IPA: /ˈɒbdʒʊɹɪt/, /ˈɒbdjʊɹɪt/, /ˈɒbdʒəɹɪt/, /-ət/
• (America) IPA: /ˈɑbd(j)ʊɹɪt/, /ˈɑbd(j)əɹɪt/, /-ət/

obdurate

1. Stubbornly persistent, generally in wrongdoing; refusing to reform or repent.

   Synonyms: obdure

   • 1594–1597, Richard Hooker, edited by J[ohn] S[penser], Of the Lawes of Ecclesiastical Politie, […], London: […] Will[iam] Stansby [for Matthew Lownes], published 1611, →OCLC ↗, (please specify the page):

     […] sometimes the very custom of evil making the heart obdurate against whatsoever instructions to the contrary […]

   • 1594, [William Shakespeare], Venus and Adonis, 2nd edition, London: […] Richard Field, […], →OCLC ↗, [verse 34 ↗], lines [199–200]:

     Art thou obdurate, flintie, hard as ſteele? / Nay more then flint, for ſtone at raine relenteth: […]

   • 1667, John Milton, “Book I”, in Paradise Lost. […], London: […] [Samuel Simmons], and are to be sold by Peter Parker […]; [a]nd by Robert Boulter […]; [a]nd Matthias Walker, […], →OCLC ↗; republished as Paradise Lost in Ten Books: […], London: Basil Montagu Pickering […], 1873, →OCLC ↗, lines 56–58:

     […] round he throws his baleful eyes
     That witness'd huge affliction and dismay
     Mixt with obdurate pride and stedfast hate:

   • 1818, Percy Bysshe Shelley, “(please specify the page)”, in The Revolt of Islam; […], London: […] [F]or C[harles] and J[ames] Ollier, […]; by B[uchanan] M‘Millan, […], →OCLC ↗, stanza 9:

     But custom maketh blind and obdurate
     The loftiest hearts.

2. (obsolete) Physically hardened, toughened.
   • 2012, Stephen King, 11/22/63, page 827:

     The past is obdurate for the same reason a turtle's shell is obdurate: because the living flesh inside is tender and defenseless.

3. Hardened against feeling; hard-hearted.
   • 1847 January – 1848 July, William Makepeace Thackeray, chapter 13, in Vanity Fair […], London: Bradbury and Evans […], published 1848, →OCLC ↗:

     I fear the gentleman to whom Miss Amelia's letters were addressed was rather an obdurate critic.

• (stubbornly persistent in wrongdoing): hardened, hard-hearted, impertinent, intractable, unrepentant, unyielding, recalcitrant

• durable, duration
• endure, endurance, enduring

• French: opiniâtre, têtu
• German: stur, hartnäckig
• Russian: упря́мый

• French: dur comme un roc
• German: hart
• Russian: закалённый

obdurate (obdurates, present participle obdurating; simple past and past participle obdurated)

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