11
unresolved(adjective, uncertain, settled)
5
undetermined
3
insoluble(adjective, unable, answered)
3
undecided
3
unexplained
2
unsettled
2
dissonant
2
open
2
uncertain
1
impenetrable
1
irresolute
1
mysterious
1
mystifying
1
odd
1
outstanding
1
strange
1
unanswered
1
unconcluded
1
undisclosed
1
undiscovered
11 years ago|2.3k views|share |citing 
APASmart Define. (2015). unsolved thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/unsolved/thesaurus/synonyms
ChicagoSmart Define. 2015. "unsolved thesaurus" https://smartdefine.org/unsolved/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2015, unsolved thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/unsolved/thesaurus/synonyms>.
MLASmart Define. "unsolved thesaurus" 14 April 2015. Web. 20 September 2026. <https://smartdefine.org/unsolved/thesaurus/synonyms>