Unsolved problem
Synonyms for Unsolved problem
- puzzle
- quandary
- poser
- question
- problem
- secret
- riddle
- conundrum
- enigma
- mystery
- brainteaser
- stumper
- ruddles
- paradox
- question mark
- closed book
- brain-teaser
- Chinese puzzle
For more similar words, try Unsolved problem on Thesaurus.plus dictionary