Definition - What does Tombstoned mean?
Tombstoned is the state of an application that does not have a device cache record of its last active state. An application is tombstoned if it is intentionally or unintentionally closed, halted or disturbed by a user, system or other operation, and cannot be stored because the device cache is too low.
Techopedia explains Tombstoned
A tombstoned application is visible in mobile or handheld devices with acute cache memory. Tombstoning typically occurs when an application stops in the middle of an operation. If the device memory or cache has sufficient memory, the current state is stored. However, if there is not enough memory, all the application’s state data, including running processes and session calls, are discarded, and the application is tombstoned. To mitigate this problem, the application is designed to store application state data in the device's persistent storage, in order to restore the application to its last known state.