fluke

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

• noun Nautical The triangular blade at the end of an arm of an anchor, designed to catch in the ground.
• noun A barb or barbed head, as on an arrow or a harpoon.
• noun Either of the two horizontally flattened divisions of the tail of a whale.
• noun A chance occurrence.
• noun Games An accidentally good or successful stroke in billiards or pool.
• noun Any of numerous parasitic flatworms, including the trematodes, some of which infect humans, and the monogeneans, which are chiefly ectoparasites of fish.
• noun Any of various flatfishes chiefly of the genus Paralichthys, especially the summer flounder.

from The Century Dictionary.

• In whaling: To disable the flukes of, as a whale, by spading.
• To fasten, as a whale, by means of a chain or rope.
• In whaling, to use the flukes, as a fish or cetacean: often with an indefinite it.
• To gain an advantage over a competitor or opponent by accident or chance; especially, to make a scratch in billiards. See fluke, n., 5.
• noun Waste cotton.
• noun A lock of hair.
• noun The part of an anchor which catches in the ground. See anchor.
• noun One of the barbs of a harpoon or toggle-iron; a flue: called by English whalemen wither.
• noun Either half of the tail of a cetacean or sirenian: so called from its resemblance to the fluke of an anchor.
• noun In mining, an instrument used to clean a hole previous to charging it with powder for blasting.
• noun [⟨ fluke, verb] In billiards, an accidentally successful stroke; the advantage gained when, playing for one thing, one gets another; hence, any unexpected or accidental advantage or turn; a chance; a scratch.
• noun Hence— To become refractory or mutinous; make a disturbance on board ship.
• noun Hence— To go to bed; bunk or turn in.
• In shooting, to hit by a chance shot.
• noun A name given locally in Great Britain to species of flatfish.
• noun A trematoid worm; an entozoic parasitic worm of the order Trematoidea, infesting various parts of man and other animals, especially the liver, bile-ducts, etc.: so called from the resemblance of its hydatid to a fluke or flounder.
• noun A result of accident or lucky chance rather than of skill.
• noun A failure, as of a yacht-race for lack of wind.

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

• noun (Zoöl.) The European flounder. See flounder.
• noun (Zoöl.) Any American flounder of the genus Paralichthys, especially Paralicthys dentatus, found in the Atlantic Ocean and in adjacent bays.
• noun (Zoöl.) A parasitic trematode worm of several species, having a flat, lanceolate body and two suckers. Two species (Fasciola hepatica and Distoma lanceolatum) are found in the livers of sheep, and produce the disease called rot.
• noun The part of an anchor which fastens in the ground; a flook. See anchor.
• noun (Zoöl.) One of the lobes of a whale's tail, so called from the resemblance to the fluke of an anchor.
• noun An instrument for cleaning out a hole drilled in stone for blasting.
• noun Cant, Eng. An accidental and favorable stroke at billiards (called a scratch in the United States); hence, any accidental or unexpected advantage.
• verb Slang To get or score by a fluke.

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

• noun A lucky or improbable occurrence, with the implication that the occurrence could not be repeated.
• verb To obtain a successful outcome by pure chance.
• verb snooker To fortuitously pot a ball in an unintended way.
• noun A flounder.
• noun A trematode; a parasitic flatworm of the Trematoda class, related to the tapeworm.
• noun Either of the two lobes of a whale's or similar creature's tail.
• noun nautical Any of the triangular blades at the end of an anchor, designed to catch the ground.
• noun A metal hook on the head of certain staff weapons (such as a bill), made in various forms depending on function, whether used for grappling or to penetrate armour when swung at an opponent.
• noun In general, a winglike formation on a central piece.

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

• noun a stroke of luck
• noun a barb on a harpoon or arrow
• noun either of the two lobes of the tail of a cetacean
• noun flat bladelike projection on the arm of an anchor
• noun parasitic flatworms having external suckers for attaching to a host