43 entries under idiom topic. ×

28
closed book(noun, expression, trouble, challenge)
8
mystery story(noun, expression, question, secret)
6
crossword puzzle(noun, expression, difficult, issue)
6
fair question(noun, expression, question, secret)
5
bone of contention(noun, expression, question, secret)
5
crux criticorum(noun, expression, secret, brain)
5
field of inquiry(noun, expression, question, secret)
5
knotty point(noun, expression, question, secret)
5
matter in dispute(noun, expression, question, secret)
5
moot point(noun, expression, question, secret)
4
brain twister(noun, expression, difficult, issue)
4
vexed question(noun, expression, trouble, challenge)
4
diagnus vindice nodus(noun, expression, problem, secret)
4
jigsaw puzzle(expression, secret, mystery, brain-twister)
4
open question(noun, expression, question, secret)
4
plain question(noun, expression, question, secret)
4
point in dispute(noun, expression, question, secret)
4
question at issue(noun, expression, question, secret)
4
sealed book(noun, expression, problem, secret)
4
sixty-four dollar question(noun, expression, question, secret)
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APASmart Define. (2016). enigma thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/enigma/thesaurus/synonyms
ChicagoSmart Define. 2016. "enigma thesaurus" https://smartdefine.org/enigma/thesaurus/synonyms (accessed September 25, 2026).
HarvardSmart Define 2016, enigma thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/enigma/thesaurus/synonyms>.
MLASmart Define. "enigma thesaurus" 1 April 2016. Web. 25 September 2026. <https://smartdefine.org/enigma/thesaurus/synonyms>