shark

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of numerous chiefly marine carnivorous fishes of the class Chondrichthyes (subclass Elasmobranchii), which are sometimes large and voracious and have a streamlined torpedolike body, five to seven gill openings on each side of the head, a large oil-filled liver, a cartilaginous skeleton, and tough skin covered with small toothlike scales.
2. n. A person regarded as ruthless, greedy, or dishonest.
3. n. A vicious usurer.
4. n. Slang A person unusually skilled in a particular activity: a card shark.
5. v. Archaic To obtain by deceitful means.
6. v. To practice or live by fraud and trickery.

Century Dictionary and Cyclopedia

1. n. A selachian of the subclass Plagiostomi, of an elongate form, with the pectoral fins moderately developed, the branchial apertures lateral, and the mouth inferior (rarely terminal). Over 150 species are known as inhabitants of the modern seas, and sharks formed a very important or even predominant contingent to the faunæ of early epochs. The internal differences manifested by species having a considerable resemblance externally are so great as to have led some naturalists to propose for them three distinct orders, which have been named Anarthri, Proarthri, and Opistharthri. Most living sharka belong to the first order and represent therein 15 families, while of the Proarthri only one family with 4 species is known, and of the Opistharthri two families with 6 or 7 species. Most sharks are carnivorous, and some of them eminently so; their dentition corresponds to this character, the teeth being often compressed, with trenchant and frequently serrated edges, arranged in many rows, and folded back on the jaws, leaving only the outermost erect for action. These rows of teeth successively come into functional position. In others, however, the teeth are flattish and not erectile. In a few, also, which attain a large size, the teeth are extremely small, and the animal feeds upon very small animals, being not truly carnivorous. The skin is generally covered with small scales or plates firmly adherent to the skin and overlapping, forming shagreen. (See cut under scale.) But various deviations are manifested in different forms, and in one, Echinorhinidæ, the surface is mostly naked, only some thorn-like plates being developed. Sharks inhabit for the most part tropical and warm waters; the larger ones live in the open sea, but a few species extend into high north and south latitudes. The largest shark is Rhinodon typicus, the whale-shark, said to attain a length of over 50 feet. Next in size is the great basking-shark, Cetorhinus maximus, which is reported occasionally to reach a length of 40 feet. (See Cetorhinus, and cut under basking-shark.) Another large species is Carcharodon rondeleti, among those known as man-eaters. The ordinary carnivorous sharks belong to the family Galeorhinidæ or Carchariidæ, as the common blue sharks. The topes also belong to this family. (See cut under Galeorhinus.) The hammer-headed sharks belong to the family Sphyrnidæ or Zygænidæ. Fox-sharks or threshers are: Alopeciidæ. The porbeagles or mackerel-sharks are Lamnidæ. (See cut under mackerel-shark.) Gray sharks or cow-sharks are Notidanidæ. (See cut under Hexanchus.) Dogfishes are sharks of the families Spinacidæ and Scylliorhinidæ. False sharks are the chimeras or Holocephali.
2. To fish for or catch sharks.
3. n. A sharper; a cheat; a greedy, dishonest fellow who eagerly preys upon others; a rapacious swindler.
4. n. The sharp practice and petty shifts and stratagems of a swindler or needy adventurer.
5. To play the shark or needy adventurer; live by one's wits; depend on or practise the shifts and stratagems of a needy adventurer; swindle: sometimes with an impersonal it: as, to shark for a living.
6. To pick up; obtain or get together by sharking: with up or out.

Wiktionary

1. n. A scaleless, predatory fish of the superorder Selachimorpha, with a cartilaginous skeleton and 5 to 7 gill slits on each side of its head.
2. n. informal, derogatory A sleazy and amoral lawyer; an ambulance chaser.
3. n. informal A relentless and resolute person or group, especially in business.
4. n. informal A very good poker or pool player.
5. n. A person who feigns ineptitude to win money from others.
6. v. obsolete To steal or obtain through fraud.
7. v. obsolete, intransitive To play the petty thief; to practice fraud or trickery; to swindle.
8. v. obsolete, intransitive To live by shifts and stratagems.

GNU Webster's 1913

1. n. (Zoöl.) Any one of numerous species of elasmobranch fishes of the order Plagiostomi, found in all seas.
2. n. colloq. A rapacious, artful person; a sharper.
3. n. obsolete Trickery; fraud; petty rapine.
4. v. obsolete To pick or gather indiscriminately or covertly.
5. v. To play the petty thief; to practice fraud or trickery; to swindle.
6. v. To live by shifts and stratagems.

WordNet 3.0

1. v. play the shark; act with trickery
2. n. any of numerous elongate mostly marine carnivorous fishes with heterocercal caudal fins and tough skin covered with small toothlike scales
3. v. hunt shark
4. n. a person who is ruthless and greedy and dishonest
5. n. a person who is unusually skilled in certain ways