accustomed; hardened; used
When I first moved from India to Norway, I found the winter cold almost unbearable, but over the ten years that I have lived here, I have become inured to it.
in ure (in practice) (Latin)
someone INJURED again and again will become TOUGH I NU (knew) that RED iron would *harden* when it cools down and after that it would be *accustomed* to further exposures. To become INURED you must have ENDURED.