mark n.1
[SE mark, to note down, i.e. one who is noted down as a possible victim]
1. (orig. UK Und.) the potential and actual victim of a con-man, a gullible person; thus make a mark, to ensnare a victim.
2. (UK Und.) an item to be stolen, a place to be robbed.
3. (UK Und.) a pickpocket’s target.
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