unsolved problem

Synonyms

enigma puzzle riddled conundrum closed book brain-teaser loose end

Examples

Search is an unsolved problem. Marissa Mayer

Nausea is an unsolved problem of medicine and marijuana is the finest anti-nausea medication known to science. Peter McWilliams

Words in the phrase

unsolved problem

Close letter words and terms

unsolve unsolved unsolved challenge unsomber unsombre unsonable