insidious
Gradually, secretly dangerous
Insidious is an adjective that negatively characterizes something that is designed to trap someone with enticement: Recreational drugs have an insidious appeal.
Insidious also describes detrimental effects that develop gradually: the insidious onset of clinical depression.
Threats, diseases, and plots are typically characterized as insidious.
Causing false beliefs
- deceptiveCreating false impressions
- duplicitousDeliberately deceptive in nature
- dissemblingConcealing true motives
- disingenuousFeigning ignorance or innocence
specious · treacherous · perfidious · false · two-faced · underhanded · guileful · deceitful
Disloyal and dangerous
- perfidiousDeliberately breaking faith
- backstabbingCovert betrayal of trust
- double-dealingDeceptive practice of betrayal
- traitorousGuilty of betrayal
disloyal · faithless · false-hearted · Judas · quisling · turncoat · betrayer · sellout
Threateningly suggestive of harm
- malevolentHarboring ill will
- maliciousMeaning to do harm
- evilProfound moral wickedness
- nefariousExtremely evil or villainous
wicked · scheming · calculating · conniving · plotting · machinating · devious · cunning
Not immediately obvious
- surreptitiousDone secretly, avoiding detection
- covertIntentionally concealed
- furtiveSecretive and sly
- stealthySecretly cautious in movement
sneaking · creeping · lurking · unnoticed · unobtrusive · imperceptible · invisible · hidden
Gradually and subtly harmful
- creepingMoving slowly, stealthily
- slow-actingTaking effect gradually
- cumulativeIncreasing by successive additions
- progressiveFavoring reform and innovation
erosive · corrosive · festering · metastatic · spreading · incremental · imperceptible · undetected
misleading
Causing false beliefs
- deceptiveCreating false impressions
- duplicitousDeliberately deceptive in nature
- dissemblingConcealing true motives
disingenuous · specious · treacherous · perfidious · false · two-faced · underhanded · guileful · deceitful · fraudulent
treacherous
Disloyal and dangerous
- perfidiousDeliberately breaking faith
- backstabbingCovert betrayal of trust
- double-dealingDeceptive practice of betrayal
traitorous · disloyal · faithless · false-hearted · Judas · quisling · turncoat · betrayer · sellout
sinister
Threateningly suggestive of harm
- malevolentHarboring ill will
- maliciousMeaning to do harm
- evilProfound moral wickedness
nefarious · wicked · scheming · calculating · conniving · plotting · machinating · devious · cunning · crafty
subtle
Not immediately obvious
- surreptitiousDone secretly, avoiding detection
- covertIntentionally concealed
- furtiveSecretive and sly
stealthy · sneaking · creeping · lurking · unnoticed · unobtrusive · imperceptible · invisible · hidden · concealed
pernicious
Gradually and subtly harmful
- creepingMoving slowly, stealthily
- slow-actingTaking effect gradually
- cumulativeIncreasing by successive additions
progressive · erosive · corrosive · festering · metastatic · spreading · incremental · imperceptible · undetected · silent
- deceptionlie, lies, lying, fake, fraud
- cunningcunning, craftiness, crafty, guile, slyness
- wickedevil, wicked, villainous, malicious, sinister
- medical stagesacute phase, recovery phase, late stage, early-stage, advanced stage
insidiousovert
Plainly apparent to all
open · obvious · blatant · conspicuous · direct
insidiousstraightforward
Clear and uncomplicated
direct · honest · sincere · forthright · candid