slyPronunciation: (slī), [key]
—adj., sly•er or sli•er, sly•est or sli•est,
cunning or wily: sly as a fox.
stealthy, insidious, or secret.
playfully artful, mischievous, or roguish: sly humor.
on the sly,
secretly; furtively: a tryst on the sly.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.