65 entries under underground topic. ×

1
esoteric(obscure, unknown, clandestine, undisclosed)
1
hush-hush(adjective, quiet, reserved, secret, private)
1
mysterious(obscure, unknown, clandestine, undisclosed)
1
recondite(obscure, unknown, clandestine, undisclosed)
1
shrouded(obscure, unknown, isolated, clandestine)
1
strange(obscure, deep, unknown, isolated, hard-hearted)
1
undisclosed(obscure, unknown, personal, clandestine)
1
unenlightened(obscure, deep, unknown, clandestine)
1
unknown(obscure, clandestine, undisclosed, unrevealed)
1
unpublished(obscure, deep, unknown, clandestine)
1
unseen(obscure, unknown, clandestine, undisclosed)
0
ambiguous(obscure, deep, unknown, clandestine)
0
backstairs(clandestine, undisclosed)
0
camouflaged(obscure, unknown, clandestine, undisclosed)
0
classified(obscure, unknown, personal, clandestine)
0
cloak-and-dagger(obscure, unknown, clandestine, undisclosed)
0
clouded(obscure, unknown, clandestine, undisclosed)
0
conspiratorial(obscure, unknown, clandestine, undisclosed)
0
discreet(personal, clandestine, undisclosed, confidential)
0
dissembled(clandestine, undisclosed)
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APASmart Define. (2015). retired thesaurus. Retrieved September 27, 2026, from https://smartdefine.org/retired/thesaurus/synonyms
ChicagoSmart Define. 2015. "retired thesaurus" https://smartdefine.org/retired/thesaurus/synonyms (accessed September 27, 2026).
HarvardSmart Define 2015, retired thesaurus, Smart Define, viewed 27 September, 2026, <https://smartdefine.org/retired/thesaurus/synonyms>.
MLASmart Define. "retired thesaurus" 10 April 2015. Web. 27 September 2026. <https://smartdefine.org/retired/thesaurus/synonyms>