50 entries under underground topic. ×

1
sub-rosa(clandestine, undisclosed)
1
surreptitious(secret, hidden, clandestine, concealed)
0
backdoor(obscure, clandestine, undisclosed, unrevealed)
0
backstairs(clandestine, undisclosed)
0
camouflaged(obscure, clandestine, undisclosed, unrevealed)
0
classified(obscure, clandestine, undisclosed, unrevealed)
0
cloak-and-dagger(obscure, clandestine, undisclosed, unrevealed)
0
closet(obscure, clandestine, undisclosed, unrevealed)
0
confidential(clandestine, undisclosed)
0
conspiratorial(obscure, clandestine, undisclosed, unrevealed)
0
discreet(clandestine, undisclosed)
0
dissembled(clandestine, undisclosed)
0
dissimulated(clandestine, undisclosed)
0
hush-hush(clandestine, undisclosed)
0
in ambush(expression, clandestine, undisclosed)
0
inside(clandestine, undisclosed)
0
on the QT(expression, idiom, obscure, clandestine)
0
restricted(clandestine, undisclosed)
0
sly(clandestine, undisclosed)
0
sneak(clandestine, undisclosed)
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APASmart Define. (2015). unknown thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/unknown/thesaurus/synonyms
ChicagoSmart Define. 2015. "unknown thesaurus" https://smartdefine.org/unknown/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2015, unknown thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/unknown/thesaurus/synonyms>.
MLASmart Define. "unknown thesaurus" 10 April 2015. Web. 22 September 2026. <https://smartdefine.org/unknown/thesaurus/synonyms>