48 entries under unknown topic. ×
| clandestine(adjective, secret, hidden, sly) | |
| secret(adjective, hidden, spy, concealed) | |
| buried(verb, adjective, secret, hidden) | |
| covert(adjective, secret, hidden, concealed) | |
| surreptitious(adjective, secret, hidden, concealed) | |
| undercover(adjective, secret, hidden, spy) | |
| covered(adjective, obscure, hidden, concealed) | |
| hidden(verb, adjective, secret, concealed) | |
| concealed(adjective, secret, hidden, spy) | |
| cloak-and-dagger(adjective, obscure, hidden, clandestine) | |
| furtive(adjective, obscure, secret, hidden) | |
| private(adjective, obscure, secret, hidden) | |
| deep(adjective, obscure, down, far) | |
| secluded(adjective, obscure, secret, hidden) | |
| clouded(obscure, secret, hidden, concealed) | |
| mysterious(adjective, obscure, secret, hidden) | |
| occult(noun, obscure, secret, hidden) | |
| abstruse(obscure, secret, hidden, concealed) | |
| close(obscure, secret, hidden, concealed) | |
| closet(obscure, hidden, clandestine, fraudulent) |
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| APA | Smart Define. (2015). underground thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/underground/thesaurus/synonyms |
| Chicago | Smart Define. 2015. "underground thesaurus" https://smartdefine.org/underground/thesaurus/synonyms (accessed September 20, 2026). |
| Harvard | Smart Define 2015, underground thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/underground/thesaurus/synonyms>. |
| MLA | Smart Define. "underground thesaurus" 3 November 2015. Web. 20 September 2026. <https://smartdefine.org/underground/thesaurus/synonyms> |