adjective
sly
SLYE/slaɪ/
Cleverly concealing intentions, often playfully.
The sly player slips an extra token into his hand unnoticed.

Etymology
Old Norse slœgr meant “cunning” or “crafty,” but early English sly could praise someone as skillful, wise, or prudent. The deceitful sense turns that cleverness toward concealment and manipulation.
In context
And people who knew Cortés that he was kind of a sly dog started mocking the governor saying, "You know, governor, um you shouldn't trust Cortés.
More examples
- She gave him a sly smile.
- His sly remark hinted at the surprise.
- The fox looked slyer than its clumsy pursuer in the cartoon.
Forms
sly · slyer · slyest · slier · sliest
Similar words
- cunning
- Cunning can sound more calculating or deceptive.
- crafty
- Crafty emphasizes skillful tricks rather than playful concealment.