56 entries under hidden topic. ×
| unrevealed(obscure, secret, unknown, concealed) | |
| unseen(obscure, secret, unknown, concealed) | |
| veiled(obscure, secret, unknown, clandestine) | |
| artful | |
| cloak and dagger(expression, idiom, fraudulent) | |
| creep(secret, spy, covert) | |
| foxy | |
| fraudulent | |
| illegitimate | |
| illicit | |
| in holes and corners(expression, idiom, fraudulent) | |
| incognito(secret, spy, clandestine, undisclosed) | |
| intelligence(secret, spy, covert) | |
| spy(secret, covert) | |
| stealth(secret, spy, covert) | |
| sub-rosa(secret, spy, clandestine, undisclosed) |
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| APA | Smart Define. (2015). underground thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/underground/thesaurus/synonyms |
| Chicago | Smart Define. 2015. "underground thesaurus" https://smartdefine.org/underground/thesaurus/synonyms (accessed September 23, 2026). |
| Harvard | Smart Define 2015, underground thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/underground/thesaurus/synonyms>. |
| MLA | Smart Define. "underground thesaurus" 3 November 2015. Web. 23 September 2026. <https://smartdefine.org/underground/thesaurus/synonyms> |