6
canny(adjective, mean, smooth, sharp, cunning)
6
clever(adjective, sensitive, intelligent, cunning, deceitful)
6
perilous(adjective, characteristic, tricky, sneaky, guile)
6
sinister(adjective, characteristic, guile, insidiousness)
6
two-faced(adjective, false, dishonest, cunning, deceitful)
5
secret(adjective, sneaky, characteristic, mean, smooth)
5
sharp(adjective, mean, smooth, cunning, deceitful)
5
unscrupulous(adjective, mean, smooth, dishonest, cunning)
4
deceiving(adjective, characteristic, deception, false, deceit)
4
delusive(adjective, characteristic, mean, smooth, deception)
4
delusory(adjective, characteristic, deception, false, deceit)
4
dishonorable(adjective, characteristic, mean, smooth, dishonest)
4
fallacious(adjective, characteristic, false, deceit, delusion)
4
hypocritical(adjective, characteristic, deceit, delusion)
4
illusive(adjective, characteristic, deception, false, deceit)
4
illusory(adjective, characteristic, mean, smooth, deception)
4
mischievous(adjective, mean, smooth, wicked, cunning)
4
plotting(adjective, mean, smooth, cunning, knowing)
4
serpentine(adjective, false, misleading, illusory)
4
shady(adjective, dishonest, cunning, deceitful, dubious)
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APASmart Define. (2015). insidious thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/insidious/thesaurus/synonyms
ChicagoSmart Define. 2015. "insidious thesaurus" https://smartdefine.org/insidious/thesaurus/synonyms (accessed September 24, 2026).
HarvardSmart Define 2015, insidious thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/insidious/thesaurus/synonyms>.
MLASmart Define. "insidious thesaurus" 14 April 2015. Web. 24 September 2026. <https://smartdefine.org/insidious/thesaurus/synonyms>