1. A difficult problem that is not well-known, difficult to understand, or hard to identify and solve
The software engineer spent weeks debugging an obscure problem in the legacy code.
O engenheiro de software passou semanas depurando um problema obscuro no código legado.
2. A complex issue that is unclear or ambiguous in nature and requires investigation
They finally solved the obscure problem that had been plaguing the system for months.
Finalmente resolveram o problema obscuro que tinha estado afligindo o sistema por meses.