furtive
Definitions
Attempting to avoid notice or attention, typically because of guilt or a belief that discovery would lead to trouble.
Suggestive of guilty nervousness; secretive or stealthy.
Examples
He cast a furtive glance at his watch, hoping no one would notice he was bored.
The cat made a furtive movement toward the kitchen counter when it thought no one was looking.
They exchanged a furtive smile across the crowded room, keeping their secret hidden from the others.
Synonyms
secretive stealthy surreptitious sneaky sly covert clandestine