As a noun thief
is one who has carried out a theft.
As an adjective furtive is
One who has carried out a theft.
(obsolete) A waster in the snuff of a candle.
- (Bishop Hall)
* cat burglar
Exhibiting guilty or evasive secrecy.
* 1949 , George Orwell, Nineteen Eighty-Four , p31
- But that was merely a piece of furtive knowledge which he happened to possess because his memory was not satisfactorily under control.
* (stealthy) surreptitious
* See also