63 entries under underground topic. ×

13
obscure(adjective, hard, obscure, rough, difficult)
8
mysterious(adjective, hard, obscure, solid, dark)
7
ambiguous(adjective, obscure, rough, dark, uncertain)
5
dark(adjective, hard, obscure, rough, solid)
3
covert(clandestine, undisclosed, concealment)
3
cryptic(adjective, obscure, difficult, dark, uncertain)
3
secret(adjective, obscure, dark, superior, uncertain)
2
abstruse(adjective, hard, obscure, difficult, delicate)
2
hidden(adjective, hard, obscure, solid, dark)
2
recondite(adjective, obscure, dark, uncertain, mysterious)
2
undisclosed(obscure, unknown, clandestine, concealment)
2
unseen(obscure, unknown, clandestine, undisclosed)
1
arcane(adjective, obscure, difficult, solid, strange)
1
clouded(adjective, obscure, uncertain, doubtful, dubious)
1
mystic(adjective, obscure, solid, dark, superior)
1
reticent(obscure, deep, unknown, clandestine)
0
backdoor(obscure, deep, unknown, clandestine)
0
backstairs(clandestine, undisclosed)
0
camouflaged(obscure, unknown, clandestine, undisclosed)
0
clandestine
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APASmart Define. (2016). unintelligible thesaurus. Retrieved September 29, 2026, from https://smartdefine.org/unintelligible/thesaurus/synonyms
ChicagoSmart Define. 2016. "unintelligible thesaurus" https://smartdefine.org/unintelligible/thesaurus/synonyms (accessed September 29, 2026).
HarvardSmart Define 2016, unintelligible thesaurus, Smart Define, viewed 29 September, 2026, <https://smartdefine.org/unintelligible/thesaurus/synonyms>.
MLASmart Define. "unintelligible thesaurus" 30 March 2016. Web. 29 September 2026. <https://smartdefine.org/unintelligible/thesaurus/synonyms>