Bedeutung von “sly” — Learner’s Dictionary

sly

adjective us uk /slaɪ/ slyer, slyest

deceiving people in a clever way to get what you want

sly smile

a smile that shows you know something that other people do not:

"I know why Chris didn't come home yesterday," she said with a sly smile.
slyly adverb

(Definition von “sly” aus dem Cambridge Learner's Dictionary © Cambridge University Press)