indestructible
adj.adj. impossible to break or destroy. You use this to describe something that is very strong and will last forever.
adj. impossible to destroy or demolish; resilient enough to withstand extreme force or wear. Often used figuratively to describe abstract concepts like spirit or hope.
These plastic toys are practically indestructible.
The black box on an airplane is designed to be indestructible so it can survive a crash.
While the physical structures of the city were leveled during the war, the indestructible spirit of its inhabitants allowed them to rebuild from the ruins within a single generation.
From in- + destructible.
Often follows a linking verb like 'be' or 'seem'; frequently modified by adverbs of degree like 'virtually' or 'practically'.