Conundrum (noun)

1. A problem or puzzle that is difficult to solve or understand.
2. A situation that is difficult to explain or understand.

Origin:

Derived from the welsh word "cwmnwdm" in the 16th century, meaning "a riddle in the form of a question".

Examples:

1. The conundrum of how to increase profits while reducing costs has been a topic of much discussion.
2. It's a conundrum as to how to balance the needs of the company with the needs of the employees.
3. The conundrum of how to reconcile the two conflicting interests is a difficult one to solve.
4. The conundrum of how to improve the performance of the system remains unresolved.
5. It's a conundrum as to how to reduce the environmental impact of the project.