Indestructible
Part of speech: adjective
Definition: Not destructible; incapable of decomposition or of being destroyed.
Example sentence: The older view of the nature of heat was that it is a substance, very fine and imponderable indeed, but indestructible, and unchangeable in quantity, which is an essential fundamental property of all matter.
Undestroyable
Part of speech: adjective
Definition: Not able to be destroyed; indestructible.