75 entries under noun topic. ×

36
enigma(trouble, challenge, question, puzzle)
28
mystery(trouble, challenge, unknown, puzzle)
22
occult(adjective, evil, obscure, dark)
22
riddle(trouble, challenge, question, puzzle)
20
conundrum(trouble, challenge, question, puzzle)
16
closed book(expression, idiom, trouble, challenge)
14
puzzle(trouble, challenge, question, mystery)
13
unknown(adjective, obscure, dark, superior)
13
unrevealed(adjective, obscure, dark, mysterious)
12
arcanum
11
brain-teaser(trouble, challenge, question, puzzle)
7
confidence(hint, exclusive, buzz, gossip)
5
trick
5
whodunit(question, puzzle, perplexity, obscurity)
4
code(confidence, mystery, unrevealed, enigma)
4
mystery story(expression, idiom, mystery)
4
obscurity(vagueness, ambiguity, secrecy, anonymity)
4
oracle(question, confidence, puzzle, obscurity)
4
puzzlement(trouble, challenge, question, puzzle)
3
key(confidence, means, interpretation, mystery)
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APASmart Define. (2016). secret thesaurus. Retrieved September 28, 2026, from https://smartdefine.org/secret/thesaurus/synonyms
ChicagoSmart Define. 2016. "secret thesaurus" https://smartdefine.org/secret/thesaurus/synonyms (accessed September 28, 2026).
HarvardSmart Define 2016, secret thesaurus, Smart Define, viewed 28 September, 2026, <https://smartdefine.org/secret/thesaurus/synonyms>.
MLASmart Define. "secret thesaurus" 31 March 2016. Web. 28 September 2026. <https://smartdefine.org/secret/thesaurus/synonyms>