He refused, and when the officer politely but firmly insisted he remained obdurate .
stubborn, unbending, obstinate, intransigent, inflexible, unyielding open-handedness, largess
لجوج، سخت دل، سنگ دل
( Test )
It is only the obdurate criminal that is worthy of our indignation.
Source: Edgar Huntly or, Memoirs of a Sleep-Walker
In this sentence, obdurate means: