insidious Synonyms

deceptive guileful sly subtle designing treacherous deceitful crafty wily pernicious artful scheming sneaky sneaking snaky smooth playing games puckish slick shrewd shifty stealthy subtile vulpine machiavellian underhand tricky tricksy obliquitous treasonable wormlike surreptitious not straightforward faking one out duplicitous pervasive perilous arch dangerous cunning crooked covert corrupt clever circumventive canny calculating beguiling backhanded deep