66 entries under underground topic. ×

6
unknown(adjective, clandestine, undisclosed, nameless)
3
incognito(close, unknown, clandestine, undisclosed)
2
hidden(clandestine, undisclosed)
2
mysterious(adjective, clandestine, undisclosed)
2
obscure(unknown, clandestine, undisclosed, anonymous)
1
backdoor(close, sensitive, inside, clandestine)
1
backstairs(close, sensitive, inside, clandestine)
1
camouflaged(close, clandestine, undisclosed, furtive)
1
clandestine(adjective, undisclosed)
1
classified(sensitive, clandestine, undisclosed, sub-rosa)
1
close(inside, clandestine, undisclosed, furtive)
1
confidential(adjective, clandestine, undisclosed)
1
covert(clandestine, undisclosed)
1
cryptic(close, inside, clandestine, undisclosed)
1
discreet(close, inside, clandestine, undisclosed)
1
disguised(clandestine, undisclosed)
1
dissembled(close, clandestine, undisclosed, furtive)
1
dissimulated(close, inside, clandestine, undisclosed)
1
furtive(close, clandestine, undisclosed)
1
hush-hush(clandestine, undisclosed)
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APASmart Define. (2015). unacknowledged thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/unacknowledged/thesaurus/synonyms
ChicagoSmart Define. 2015. "unacknowledged thesaurus" https://smartdefine.org/unacknowledged/thesaurus/synonyms (accessed September 26, 2026).
HarvardSmart Define 2015, unacknowledged thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/unacknowledged/thesaurus/synonyms>.
MLASmart Define. "unacknowledged thesaurus" 14 April 2015. Web. 26 September 2026. <https://smartdefine.org/unacknowledged/thesaurus/synonyms>