c.1200, from O.N. sloegr "cunning, crafty, sly," from P.Gmc. *slogis (cf. Low Ger. slu "cunning, sly"), probably from base *slog- "hit" (see
slay), with an original notion of "able to hit." Cf. Ger. verschlagen "cunning, crafty, sly," schlagfertig "quick-witted," lit. "ready