furtive

Short definition from Wiktionary

Adjective

1. 1
   Of a thing: done with evasive or guilty secrecy.
2. 2
   Of a thing: that has been acquired by theft; stolen; also (generally) taken stealthily.
3. 3
   Of a person or an animal: sly, stealthy.
4. 4
   Of a person, etc.: inclined to steal; pilfering, thieving.