Sly, a. [Compar. Slier or Slyer; superl. Sliest or Slyest.]
Etymology: [OE. sli, slegh, sleih, Icel sl, for sl; akin to Sw. slug, Dan. slu, LG. slou, G. schlau; probably to E. slay, v.t.; cf. G. verschlagen sly. See Slay, v. t., and cf. Sleight.]
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.
2. Artfully cunning; secretly mischievous; wily. For my sly wiles and subtle craftiness, The litle of the kingdom I possess. Spenser.
3. Done with, and marked by, artful and dexterous secrecy; subtle; as, a sly trick. Envy works in a sly and imperceptible manner. I. Watts.
4. Light or delicate; slight; thin. [Obs.] By the sly, or On the sly, in a sly or secret manner. [Colloq.] "Gazed on Hetty's charms by the sly." G. Eliot. -- Sly goose (Zoöl.), the common sheldrake; -- so named from its craftiness.
1 more senses
Syn. -- Cunning; crafty; subtile; wily. See Cunning.
1 other Webster entry under this spelling
Sly, adv.
Slyly. [Obs. or Poetic] Spenser.
Shades of meaning
Fernald lists sly only as an antonym, under candid.
He lists it without comment; the entries above explain its neighbors.