What does "shark" mean?

Additional senses

1. 2.Trickery; fraud; petty rapine; as, to live upon the shark. [Obs.] South. Baskin shark, Liver shark, Nurse shark, Oil shark, Sand shark, Tiger shark, etc. See under Basking, Liver, etc. See also Dogfish, Houndfish, Notidanian, and Tope. -- Gray shark, the sand shark. -- Hammer-headed shark. See Hammerhead. -- Port Jackson shark. See Cestraciont. -- Shark barrow, the eggcase of a shark; a sea purse. -- Shark ray. Same as Angel fish (a), under Angel. -- Thrasher shark, or Thresher shark, a large, voracious shark. See Thrasher. -- Whale shark, a huge harmless shark (Rhinodon typicus) of the Indian Ocean. It becomes sixty feet or more in length, but has very small teeth.
2. 3.To pick or gather indiscriminately or covertly. [Obs.] Shak.
3. 4.To play the petty thief; to practice fraud or trickery; to swindle. Neither sharks for a cup or a reckoning. Bp. Earle.
4. 5.To live by shifts and stratagems. Beau & Fl.