Meaning

adjective marked by skill in deception

originFrom Middle English sly, sley, sleigh, sleiȝ, from Old Norse slǿgr (“sly, cunning”, literally “capable of hitting or striking”), from Proto-Germanic *slōgiz (“lively, agile, cunning, sly, striking”), from Proto-Indo-European *slak- (“to hit, throw”). Cognate with Icelandic slægur (“crafty, sly”), Norwegian Nynorsk sløg (“sly”). Related to sleight, slay. In all likelihood, however, unrelated with…

Etymology from Wiktionary, CC BY-SA 3.0