13
false(adjective, characteristic, dishonest, tricky, treacherous)
13
shifty(adjective, smooth, false, dishonest, deceitful)
12
devious(adjective, characteristic, sharp, dishonest, cunning)
12
Machiavellian(adjective, characteristic, guile, insidiousness, treachery)
12
disingenuous(adjective, guile, insidiousness, characteristic, false)
11
surreptitious(adjective, sneaky, guile, insidiousness, characteristic)
10
corrupt(adjective, characteristic, tricky, sneaky, guile)
10
smooth(adjective, guile, insidiousness, characteristic, mean)
9
astute(adjective, cunning, characteristic, smooth, sharp)
9
deep(adjective, devious, cunning, characteristic, smooth)
9
duplicitous(adjective, tricky, sneaky, guile, insidiousness)
9
scheming(adjective, dishonest, deceitful, shrewd, sly)
8
arch(cunning, adjective, characteristic, mean, smooth)
8
shrewd(adjective, smooth, sharp, dishonest, cunning)
8
sneaking(adjective, guile, insidiousness, characteristic, tricky)
7
beguiling(guileful, adjective, characteristic, false, deceit)
7
dangerous(adjective, characteristic, tricky, sneaky, guile)
7
furtive(adjective, mean, smooth, dishonest, deceitful)
7
snaky(adjective, characteristic, tricky, sly, devious)
6
calculating(adjective, dishonest, deceitful, sly, crafty)
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APASmart Define. (2015). insidious thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/insidious/thesaurus/synonyms
ChicagoSmart Define. 2015. "insidious thesaurus" https://smartdefine.org/insidious/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2015, insidious thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/insidious/thesaurus/synonyms>.
MLASmart Define. "insidious thesaurus" 14 April 2015. Web. 23 September 2026. <https://smartdefine.org/insidious/thesaurus/synonyms>