55 entries under hidden topic. ×

14
surreptitious(adjective, dishonest, secret, spy)
13
clandestine(adjective, adverb, show, dishonest, secret)
13
secret(adjective, quiet, show, dishonest)
12
covert(adjective, show, secret, reticent)
11
hush-hush(adjective, adverb, show, informal, dishonest)
11
underground(adjective, secret, unknown, spy)
9
furtive(adjective, dishonest, secret, reticent)
8
hole-and-corner(adjective, secret, private, spy)
7
confidential(adjective, secret, spy, clandestine)
7
private(adjective, secret, unknown, spy)
7
stealthy(adjective, quiet, dishonest, secret)
7
underhand(adjective, deceitful, secret, spy)
6
concealed(adjective, obscure, dishonest, secret)
6
under wraps(expression, adjective, idiom, show, dishonest)
6
secluded(adjective, secret, unknown, underground)
5
spy(adjective, secret, warning, covert)
4
occult(secret, unknown, underground, concealed)
4
underhanded(dishonest, cunning, deceitful, secret)
3
buried(adjective, secret, unknown, concealed)
3
clouded(secret, unknown, underground, concealed)
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APASmart Define. (2015). undercover thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/undercover/thesaurus/synonyms
ChicagoSmart Define. 2015. "undercover thesaurus" https://smartdefine.org/undercover/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2015, undercover thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/undercover/thesaurus/synonyms>.
MLASmart Define. "undercover thesaurus" 13 April 2015. Web. 23 September 2026. <https://smartdefine.org/undercover/thesaurus/synonyms>