71 entries under adjective topic. ×
| unconventional(secret, subversive) | |
| undisclosed(obscure, secret, unknown, hidden) | |
| unusual(secret, subversive) | |
| atypical | |
| below-ground | |
| confidential(secret, hidden, spy, clandestine) | |
| hypogeal | |
| hypogeous | |
| illegal | |
| in the recesses(expression, idiom, covered, oppressed) | |
| jumbled | |
| on the QT(expression, idiom, obscure, mysterious) | |
| on the sly(expression, idiom, unusual, secret) | |
| resistant(secret, subversive) | |
| resistive(secret, subversive) | |
| temporary | |
| unavowed | |
| unbowed(secret, subversive) | |
| abnormal | |
| dug in |
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| APA | Smart Define. (2015). underground thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/underground/thesaurus/synonyms |
| Chicago | Smart Define. 2015. "underground thesaurus" https://smartdefine.org/underground/thesaurus/synonyms (accessed September 25, 2026). |
| Harvard | Smart Define 2015, underground thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/underground/thesaurus/synonyms>. |
| MLA | Smart Define. "underground thesaurus" 3 November 2015. Web. 25 September 2026. <https://smartdefine.org/underground/thesaurus/synonyms> |