67 entries under underground topic. ×

13
underhand(adjective, honest, false, dishonest, cunning)
9
sneaky(adjective, honest, false, corrupt, dishonest)
8
furtive(adjective, dishonest, cunning, deceitful, unpredictable)
5
backstairs(clandestine, undisclosed)
2
classified(clandestine, undisclosed)
2
confidential(clandestine, undisclosed)
2
private(secret, hidden, clandestine, undisclosed)
2
sneak(clandestine, undisclosed)
2
ulterior(secret, hidden, clandestine, privy)
2
under-the-table(secret, hidden, clandestine, sneaky)
1
backdoor(clandestine, undisclosed)
1
camouflaged(secret, hidden, clandestine, undisclosed)
1
cloaked(secret, hidden, clandestine, sneaky)
1
discreet(clandestine, undisclosed)
1
disguised(secret, hidden, clandestine, sneaky)
1
dissembled(secret, hidden, clandestine, undisclosed)
1
dissimulated(clandestine, undisclosed)
1
hidden(secret, clandestine, undisclosed, sneaky)
1
in ambush(expression, clandestine, undisclosed)
1
incognito(secret, hidden, clandestine, undisclosed)
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APASmart Define. (2016). underhanded thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/underhanded/thesaurus/synonyms
ChicagoSmart Define. 2016. "underhanded thesaurus" https://smartdefine.org/underhanded/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2016, underhanded thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/underhanded/thesaurus/synonyms>.
MLASmart Define. "underhanded thesaurus" 22 January 2016. Web. 23 September 2026. <https://smartdefine.org/underhanded/thesaurus/synonyms>