- Definitions|1
- Thesaurus|74
- Abbreviations|0
41 entries under question topic. ×
| enigma(noun, trouble, challenge, secret) | |
| mystery(noun, trouble, difficulty, challenge) | |
| riddle(noun, trouble, challenge, secret) | |
| conundrum(noun, trouble, challenge, secret) | |
| secret(noun, trouble, challenge, puzzle) | |
| mystification(noun, trouble, challenge, secret) | |
| problem(noun, trouble, challenge, secret) | |
| puzzlement(noun, trouble, challenge, secret) | |
| poser(noun, trouble, challenge, secret) | |
| puzzle(noun, trouble, challenge, secret) | |
| whodunit(noun, secret, puzzle, subtlety) | |
| why(noun, trouble, difficulty, challenge) | |
| crux(noun, trouble, difficulty, challenge) | |
| sixty-four-thousand-dollar question(expression, secret, puzzle, subtlety) | |
| tough nut to crack(expression, idiom, secret, puzzle) | |
| abstruseness(difficulty, secret, puzzle, subtlety) | |
| brainteaser(difficulty, secret, puzzle, subtlety) | |
| braintwister(difficulty, secret, puzzle, subtlety) | |
| charade(secret, puzzle, subtlety, mystery) | |
| chiller(difficulty, secret, puzzle, subtlety) |
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| APA | Smart Define. (2016). closed book thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/closed_book/thesaurus/synonyms |
| Chicago | Smart Define. 2016. "closed book thesaurus" https://smartdefine.org/closed_book/thesaurus/synonyms (accessed September 22, 2026). |
| Harvard | Smart Define 2016, closed book thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/closed_book/thesaurus/synonyms>. |
| MLA | Smart Define. "closed book thesaurus" 31 March 2016. Web. 22 September 2026. <https://smartdefine.org/closed_book/thesaurus/synonyms> |