IPA: //ʌnˈrɪvjuːəbl//
KK: /ʌnˈrɪvjuəbl/
Something that cannot be examined or assessed again.
The decision made by the committee was unreviewable and final.
Unreviewable → It is formed from "un-" (meaning not) and "review" (from Latin "revidere", meaning to see again) and "-able" (meaning capable of). The word "unreviewable" means not capable of being reviewed or examined again.
Think of 'not' ('un-') being applied to something that can be 'seen again' ('review') — that's why unreviewable means it cannot be examined again.