unreturnable
/(ˌ)ʌnrɪˈtəːnəbl/adjective
1Allowing no return.
- In later use chiefly in figurative contexts with reference to death..
2That cannot be returned.
Origin
Early 16th century; earliest use found in Gavin Douglas (c1476–1522), poet and bishop of Dunkeld. From un- + returnable, in sense 1 originally after classical Latin irremeābilis irremeable.