1. Dexterous in performing an action, so as to escape notice; nimble; skillful; cautious; shrewd; knowing; in a good sense. Be ye sly as serpents, and simple as doves. (Wyclif (Matt. X. 16)) Whom graver age And long experience hath made wise and sly. (Fairfax)
Synonym: Cunning, crafty, subtile, wily. See Cunning.
Origin: OE. Sli, slegh, sleih, Icel slgr, for slgr; akin to Sw. Slug, Dan. Slu, LG. Slou, G. Schlau; probably to E. Slay, v.t.; cf. G. Verschlagen sly. See Slay, and cf. Sleight.