obdurate
OB-duh-ritadjMeaning hard-hearted and stubborn, especially when one should give way
Memory hook ob-DUR-ate: hard as DURable stone. However nicely the children ask, Rex won’t give back the ball that flew over his fence; his heart is as hard as durable stone. He is obdurate.
Even the puppy’s sad eyes could not soften the obdurate landlord.
In context The children explained, apologized and offered to pay for the window, but the neighbor remained obdurate, refusing even to listen.
Similar hard-hearted, unmoved, unyielding, stubborn
Opposite softhearted, yielding, compassionate
From Latin obdurare, “to harden,” from durus (hard).