19 entries under noun topic. ×

27
enigma(trouble, challenge, question, secret)
21
mystery(trouble, difficulty, challenge, question)
19
riddle(trouble, challenge, question, secret)
18
conundrum(trouble, challenge, question, secret)
14
secret(trouble, challenge, question, puzzle)
12
brain-teaser(trouble, challenge, puzzle, mystery)
6
mystification(trouble, challenge, question, secret)
6
problem(trouble, challenge, question, secret)
6
puzzlement(trouble, challenge, question, secret)
4
poser(trouble, challenge, question, secret)
4
puzzle(trouble, challenge, question, secret)
4
whodunit(question, secret, puzzle, subtlety)
4
why(trouble, difficulty, challenge, question)
3
arcanum
3
mystery story
2
crux(trouble, difficulty, challenge, question)
1
dilemma(trouble, challenge, puzzle)
1
head-scratcher(trouble, challenge, brainteaser)
1
perplexity(difficulty, question, secret, puzzle)
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APASmart Define. (2016). closed book thesaurus. Retrieved September 28, 2026, from https://smartdefine.org/closed_book/thesaurus/synonyms
ChicagoSmart Define. 2016. "closed book thesaurus" https://smartdefine.org/closed_book/thesaurus/synonyms (accessed September 28, 2026).
HarvardSmart Define 2016, closed book thesaurus, Smart Define, viewed 28 September, 2026, <https://smartdefine.org/closed_book/thesaurus/synonyms>.
MLASmart Define. "closed book thesaurus" 31 March 2016. Web. 28 September 2026. <https://smartdefine.org/closed_book/thesaurus/synonyms>