"Sempiternal" in the context of cryptocurrencies refers to the unalterable and enduring nature of the blockchain. Once a transaction is validated and added to the blockchain, it becomes permanent and immutable. It cannot be modified or deleted, ensuring a sempiternal and transparent historical record.
For example, if you buy Bitcoin and the transaction is recorded on its blockchain, that information will remain there forever. There is no central authority that can reverse or alter it. This feature is fundamental to trust and security in cryptocurrencies, as it guarantees the integrity of the data over time, making the transaction history a source of eternal truth.