Furtive (adjective)

1. Done by stealth; surreptitious.
2. Marked by quiet and caution and secrecy; taking pains to avoid being observed.

Origin:

From the latin word "furtivus" which means sneaky, stealthy or surreptitious.

Examples:

1. He had a furtive look on his face.
2. She had a furtive glance towards the door.
3. The furtive movements of the thief attracted attention.
4. The criminal had a furtive plan to escape.
5. The furtive behavior of the employee raised suspicion.