What's the difference between obdurate and unprayable?

Obdurate

Definition:

(a.) Hardened in feelings, esp. against moral or mollifying influences; unyielding; hard-hearted; stubbornly wicked.
(a.) Hard; harsh; rugged; rough; intractable.
(v. t.) To harden.

Example Sentences:

(1) The system is not an obdurate one-man rule, but a balancing of power groups, including the military, government and internal security, all have different interests and policies.
(2) Both the Coalition and Labor are obdurately stuck with barbaric offshore detention policies, as though sensible, humane and politically viable alternatives are beyond them.
(3) For their part, the Israeli left accused Peres of acting as a figleaf for an obdurate Likud administration.
(4) Report on the temporary substitution of pharynx and upper oesophagus with synthetic skin substitute in case of incurable obdurating neck carcinoma.
(5) His team-mates were obdurate opponents in every respect.
(6) The fact that it was Johnson rather than Crow who had been obdurate was highlighted by the fact that TfL had all along planned to retain ticket-selling facilities at several busy stations, but, prompted by Johnson, had publicly suggested that they would all be closed.
(7) For the first time there were obvious signs of tension and, suddenly, this tough, obdurate West Bromwich side showed an attacking intent that simply had not been there earlier in the match.
(8) In the face of obdurate unreason, the president of hyper-reasonableness was forced to surrender.
(9) Underpinning the witty remarks and the textbook flippancy ("call me early, Goering dear, for I'm to be Queen of the May" was apparently Nancy's riposte to news of Diana and Unity's German adventures) though, was an absolute and obdurate self-belief; a self-possessed seriousness only partly disguised by sisterly teasing.
(10) Max from Earlsfield muses: "Admittedly terrible from Fab, a shame after 47 minutes of obdurate defence.
(11) This was a slog, a result ground out against ruggedly obdurate opposition , but Chelsea may end up gaining more satisfaction from prevailing in those awkward circumstances than from some of the more comfortable strolls they have enjoyed over a nine-match winning streak.
(12) Read more It was the third minute of stoppage time, and the cruellest of circumstances for this tough, obdurate Burnley side, when Arsenal’s possession finally paid off and the seemingly endless 20th-anniversary commemorations for Arsène Wenger were given a shot of euphoria that had not seemed like coming.
(13) Ireland were obdurate opponents but that does not fully explain the lack of quality that held back England once Frank Lampard had scored the 29th goal of his international career, 10 minutes after Shane Long's expertly taken header had given Giovanni Trapattoni's side an early lead.
(14) Russia's determination to defend wider spheres of traditional influence in the non-aligned and developing world can be seen in its obdurate refusal to penalise Syria, in the face of almost universal outrage over the crackdown there; and in its de facto defence of Iran's nuclear programme.
(15) It had needed some obdurate defending to keep the score down before Alves exchanged passes with the substitute Neymar and cut in from the right to slip his shot through Hart's legs.
(16) Republicans have been both obdurate and obtuse in Congress, where approval ratings have rarely scraped 20%.
(17) He is assertive (he insists on his photographer and dictates the terms of the interview), obdurate and, at times, wilfully contrary.
(18) We had an obdurate Labor party, a feckless Senate and a very difficult media culture,” Abbott said.
(19) In the years since those facts first became known, the story of the Holocaust has been told and retold, yet it still remains obdurately difficult to tell.
(20) Giles also remained obdurate and continued to refuse to resign even though he had only four supporters as against the conspirators’ nine.