15 entries under secrecy topic. ×

1
abstruseness(difficulty, question, secret, puzzle, subtlety)
1
brainteaser(difficulty, question, secret, puzzle, subtlety)
1
braintwister(difficulty, question, secret, puzzle, subtlety)
1
charade(question, secret, puzzle, subtlety, mystery)
1
chiller(difficulty, question, secret, puzzle, subtlety)
1
difficulty(question, secret, puzzle, obscurity, subtlety)
1
inscrutability(difficulty, question, secret, puzzle, subtlety)
1
inscrutableness(difficulty, question, secret, puzzle, subtlety)
1
mindboggler(difficulty, question, secret, puzzle, subtlety)
1
occult(difficulty, question, secret, puzzle, subtlety)
1
oracle(difficulty, question, secret, puzzle, subtlety)
1
rebus(question, secret, puzzle, subtlety, mystery)
1
rune(difficulty, question, secret, puzzle, subtlety)
1
subtlety(difficulty, question, secret, puzzle, obscurity)
1
thriller(difficulty, question, secret, puzzle, subtlety)
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APASmart Define. (2016). closed book thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/closed_book/thesaurus/synonyms
ChicagoSmart Define. 2016. "closed book thesaurus" https://smartdefine.org/closed_book/thesaurus/synonyms (accessed September 25, 2026).
HarvardSmart Define 2016, closed book thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/closed_book/thesaurus/synonyms>.
MLASmart Define. "closed book thesaurus" 31 March 2016. Web. 25 September 2026. <https://smartdefine.org/closed_book/thesaurus/synonyms>