barracuda

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of various predatory marine fishes of the genus Sphyraena, having an elongated body and a projecting lower jaw with fanglike teeth.

from The Century Dictionary.

• noun A large voracious fish, Sphyræna picuda, of the West Indian and neighboring seas. It belongs to the perch family, and is from 6 to 10 feet in length.
• noun Thyrsites atun, a gempyloid fish of Australia and New Zealand: not the barracuda of American waters.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) Any of several voracious pikelike marine fishes allied to the gray mullets, constituting the genus Sphyræna and family Sphyrænidæ. The great barracuda (Sphyræna barracuda) of the West Indies, Florida, etc., is often six feet or more long, and as dangerous as a shark. In Cuba its flesh is reputed to be poisonous. Sphyræna Argentea of the Pacific coast and Sphyræna sphyræna of Europe are smaller species, and are used as food.
• noun (Zoöl.) A large edible fresh-water fish of Australia and New Zealand (Thyrsites atun).

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any large marine fish of the genus Sphyraena that have elongated bodies, a projecting lower jaw, displaying prominent fang-shaped teeth, and are aggressive predators.
• noun figuratively A unethically predatory person.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun any voracious marine fish of the genus Sphyraena having an elongated cylindrical body and large mouth with projecting lower jaw and long strong teeth