50 entries under underground topic. ×

23
obscure(adjective, knowledge, rough, dark, superior)
22
strange(adjective, person, obscure, experience, unusual)
11
hidden(verb, adjective, obscure, dark, superior)
9
secret(noun, adjective, obscure, dark, superior)
7
unacknowledged(adjective, clandestine, undisclosed, nameless)
2
clandestine(secret, hidden, concealed, undisclosed)
2
disguised(adjective, obscure, secret, hidden)
2
furtive(obscure, strange, clandestine, curious)
2
under wraps(expression, clandestine, undisclosed)
2
undercover(secret, hidden, clandestine, concealed)
2
unpublished(obscure, clandestine, undisclosed, unrevealed)
1
ambiguous(adjective, obscure, rough, anxious, worried)
1
arcane(obscure, strange, deep, mysterious, clandestine)
1
deep(obscure, mysterious, clandestine, undisclosed)
1
enigmatical(obscure, strange, clandestine, undisclosed)
1
out-of-the-way(obscure, new, clandestine, undisclosed)
1
reticent(obscure, clandestine, undisclosed, unrevealed)
1
retired(obscure, clandestine, undisclosed, unrevealed)
1
secretive(strange, clandestine, curious, concealed)
1
shrouded(obscure, secret, hidden, concealed)
<123>
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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>