Real Dictionary

fluke
If you say that something good is a fluke, you mean that it happened accidentally rather than by being planned or arranged.

fluke in American English 1
an accidentally good or lucky stroke in billiards, pool, etc.
to hit or get by a fluke
noun: the part of an anchor that catches in the ground, esp. the flat triangular piece at the end of each arm

fluke in American English 2
any of various flatfishes, esp. a genus (Paralichthys) of flounders
noun: an accidental advantage; stroke of good luck

fluke in American English 3
a pointed part of an anchor, designed to catch in the ground
noun: any of several American flounders of the genus Paralichthys, esp. P. dentatus, found in the Atlantic Ocean

fluke in British English 1
noun: a flat bladelike projection at the end of the arm of an anchor

fluke in British English 2
noun: an accidental stroke of luck
verb: to gain, make, or hit by a fluke

fluke in British English 3
noun: any parasitic flatworm, such as the blood fluke and liver fluke, of the classes Monogenea and Digenea (formerly united in a single class Trematoda)