Sly, cunning, crafty, tricky, foxy, insidious, wily, guileful, artful are comparable when they mean having or showing a disposition to attain one’s ends by devious or indirect means.
Sly implies a lack of candor which shows itself in secretiveness, in suggestiveness rather than in frankness, in underhandedness, or in furtiveness or duplicity in one’s dealings with others.
More often than the remaining words, sly is used with weakened force to imply a lightly arch or roguish quality.
Cunning (see also CLEVER 2 ) stresses the use of intelligence in overreaching or circumventing; nevertheless, it often suggests sly inventiveness rather than a high-grade mentality, and a perverted sense of morality.
Crafty also implies a use of intelligence but it usually suggests a higher order of mentality than cunning : that of one capable of devising stratagems and adroit in deception.
Tricky usually suggests unscrupulousness and chicanery in dealings with others; in general it connotes shiftiness and unreliability rather than skill in deception or in maneuvering.
Foxy implies shrewdness in dodging discovery or in practicing deceptions so that one may follow one’s own devices or achieve one’s own ends; it usually connotes experience and is rarely applied to the young or to novices.
Insidious suggests a lying in wait or a gradualness of effect or approach and applies especially to devious and carefully masked underhandedness.
Wily and guileful stress an attempt to ensnare or entrap; they usually imply treacherous astuteness or sagacity and a lack of scruples regarding the means to one’s end.
Artful implies insinuating or alluring indirectness of dealing; it usually also connotes sophistication or coquetry or clever designs.