incognita
/ɪnˈkɒɡ.nɪ.tə/Definitions
1. noun
A person or thing whose identity or nature is unknown or unexplained.
“The missing heir became a historical incognita, sparking years of research and debate.”
2. noun
A problem or situation whose nature or solution is unknown or unexplained.
“The team struggled to solve the complex incognita of the project’s budget and timeline.”