1.
difficult problem; tough question; hard challenge
A problem or question that is very hard to solve or answer. Used for academic questions, puzzles, and also figuratively for real-world challenges.
難問 covers both academic test questions and real-world challenges that are hard to resolve.
Common collocations
- 難問に挑む: to tackle a tough problem
- 難問を解く: to solve a difficult problem
- 難問を解決する: to resolve a difficult problem
- 難問奇問: bizarre and difficult questions (used for exams with unfairly tricky questions)
- 難問に直面する: to face a difficult problem