canny (adj.)youdaoicibaDictYouDict
1630s, Scottish and northern English formation from can (v.1) in its sense of "know how to," + -y (2). "Knowing," hence, "careful." A doublet of cunning that flowed into distinct senses. Often used superciliously of Scots by their southern neighbors (and their American cousins).
The Canny Scot is so well known as scarcely to require description. He carries caution, cunning, and selfishness to excess. Deceitful when a purpose is to be accomplished, he is not habitually deceitful. One thing he never loses sight of--his own interest. But of his own interest he is not the most enlightened judge. ["The Natural History of Scotsmen," in "The Argosy," December 1865]
Related: Cannily; canniness.
supercilious (adj.)youdaoicibaDictYouDict
1520s, "lofty with pride, haughtily contemptuous," from Latin superciliosus "haughty, arrogant," from supercilium "haughty demeanor, pride," literally "eyebrow" (via notion of raising the eyebrow to express haughtiness), from super "above" (see super-) + second element akin to cilium "eyelid," related to celare "to cover, hide," from PIE root *kel- (2) "to conceal" (see cell).
Since cilium is more recent than supercilium, the former can be interpreted as a back-formation to the latter .... If indeed derived from the root *kel- 'to hide', we must still assume that a noun *kilium 'eyelid' existed, since the eyelid can 'hide' the eye, whereas the eyebrow does not have such a function. Thus, supercilium may originally have meant 'what is above the cilium'. [Michiel de Vaan, "Etymological Dictionary of Latin and the other Italic Languages," Leiden, 2008]
Related: Superciliously; superciliousness.