1. in a cunning or crafty manner; with stealth or secrecy

Examples

• She slyly slipped the note into his backpack.
• He slyly avoided answering the difficult question.
• The cat slyly crept toward the unsuspecting bird.
• She slyly smiled when she heard the compliment.
• The student slyly checked his phone during class.
• He slyly suggested they take a different route home.