furtively
In a sneaky, secret way so others do not notice.
Furtively means doing something in a sneaky, secretive way because you don't want others to notice. When you act furtively, you're trying to hide what you're doing, often glancing around nervously to make sure no one is watching.
A student might furtively pass a note during class, checking first to see if the teacher is looking. A child might furtively reach for an extra cookie from the jar, moving slowly and quietly to avoid drawing attention. Someone reading ahead in a book during silent reading time might furtively turn pages when the teacher walks by.
Acting furtively doesn't always mean you're doing something wrong. You might furtively work on a surprise birthday card for your friend, hiding it quickly whenever they walk past. But the word does carry a sense of secrecy and caution. When you see someone acting furtively, glancing around with quick, nervous movements, you naturally wonder what they're trying to hide or keep secret.