95 entries under expression topic. ×

16
closed book(noun, idiom, trouble, challenge)
7
off the record(adjective, idiom, separate, private)
7
under wraps(adjective, idiom, adverb, show)
4
mystery story(noun, idiom, mystery)
3
classified information(noun, confidence, mystery, unrevealed)
3
not for publication(adjective, idiom, sensitive, private)
3
on the sly(idiom, private, hidden, sneaky)
3
out of sight
3
top secret(adjective, sensitive, private, hidden)
3
under cover(adjective, spy, covert)
2
behind the scenes(idiom, personal, confidential, hush-hush)
2
in secret
1
behind the curtain
1
beyond range(obscure, remote, faraway, far-off)
1
confidential information(noun, confidence, perplexity, mystery)
1
far back(obscure, remote, faraway, far-off)
1
glossed over(unseen, ignored, undiscovered, overlooked)
1
hush hush
1
in a cloud
1
in a fog
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APASmart Define. (2016). secret thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/secret/thesaurus/synonyms
ChicagoSmart Define. 2016. "secret thesaurus" https://smartdefine.org/secret/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2016, secret thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/secret/thesaurus/synonyms>.
MLASmart Define. "secret thesaurus" 31 March 2016. Web. 20 September 2026. <https://smartdefine.org/secret/thesaurus/synonyms>