Attested from the 16th century; with East Middle German g- for the j- sound of older Joner, which in the 15th century meant "(wrong) player"; related to the verb junen (“to play wrong”); Joner probably originally meant "Greek" and came from West Yiddish יוון (Yovon, “Greece”), יווןער (yevoner, “Greek, Ionian”), which in turn stems from the Hebrew יָוָן (yaván, “Greece”). The exact origin is unclear.
- (colloquial) crook, racketeer (one who commits crimes)
- (colloquial) sly, cunning person
- Gauner in Duden online