Synonyms|558Antonyms|116|Broader|11Narrower|9Related|411

17 entries under spy topic. ×

15
secret(adjective, unknown, hidden, concealed)
10
undercover(adjective, secret, unknown, hidden)
8
concealed(adjective, secret, unknown, hidden)
8
hole-and-corner(adjective, secret, hidden, covert)
7
furtive(adjective, obscure, secret, unknown, hidden)
7
hush-hush(adjective, secret, hidden, clandestine)
6
underhand(secret, hidden, clandestine, fraudulent)
4
stealthy(adjective, secret, hidden, clandestine)
2
under cover(expression, secret, covert)
2
underneath(secret, hidden, covert)
1
confidential(adjective, secret, hidden, clandestine)
1
on the QT(expression, adjective, idiom, obscure, mysterious)
0
creep(secret, hidden, covert)
0
incognito(secret, hidden, clandestine, undisclosed)
0
intelligence(secret, hidden, covert)
0
stealth(secret, hidden, covert)
0
sub-rosa(secret, hidden, clandestine, undisclosed)
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APASmart Define. (2015). underground thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/underground/thesaurus/synonyms
ChicagoSmart Define. 2015. "underground thesaurus" https://smartdefine.org/underground/thesaurus/synonyms (accessed September 24, 2026).
HarvardSmart Define 2015, underground thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/underground/thesaurus/synonyms>.
MLASmart Define. "underground thesaurus" 3 November 2015. Web. 24 September 2026. <https://smartdefine.org/underground/thesaurus/synonyms>