"subtle, cunning, crafty," early 14c., from wile (n.) + -ly (1). Related: Wiliness. In 16c. English had wily-pie "cunning fellow."
Entries linking to wily
wile n.
late Old English, wil "stratagem, trick, sly artifice," perhaps from Old North French *wile (Old French guile), or directly from a Scandinavian source (compare Old Norse vel "trick, craft, fraud," vela "defraud"). Perhaps ultimately related to Old English wicca "wizard" (see Wicca). Lighter sense of "amorous or playful trick" is from c. 1600.
-ly 1
suffix forming adjectives from nouns and meaning "having qualities of, of the form or nature of" (manly, lordly), "appropriate to, fitting, suited to" (bodily, earthly, daily); irregularly descended from Old English -lic, from Proto-Germanic *-liko- (Old Frisian -lik, Dutch -lijk, Old High German -lih, German -lich, Old Norse -ligr), related to *likom- "appearance, form" (Old English lich "corpse, body;" see lich, which is a cognate; see also like (adj.), with which it is identical).