black swan

Definition from Wiktionary, the free dictionary
Jump to navigation Jump to search


An Australian black swan


A calque, equivalent to black +‎ swan. Roman satirist Juvenal wrote in AD 82 of rāra avis in terris nigroque simillima cygno (a rare bird in the lands, and very like a black swan), creating a durable metaphor and expression. In the sense “unforeseen event” popularized by Nassim Nicholas Taleb in a 2007 book of the same name.[1]


  • (file)


black swan (plural black swans)

  1. Cygnus atratus, an Australian swan whose feathers are black. [c. 1700]
  2. (figuratively) Something believed impossible or not to exist, of which an example is subsequently found.
  3. (figuratively, also attributive) A rare and hard-to-predict event with major consequences.
    • 2011 March 19, Jeff Sommer, “A Crisis That Markets Can’t Grasp”, in New York Times[1]:
      In the face of black swans — also known as fat-tail events, for the way their occurrences are distributed along a probability curve — market pricing may be impossible.
    • 2011 June 29, Azam Ahmed, “New Investment Strategy: Preparing for End Times”, in New York Times[2]:
      Worried that Greece could go belly up? So-called black swan funds — named for rare and unexpected events — offer a way to profit in the event of a market collapse.



Derived terms[edit]

See also[edit]


Further reading[edit]


  1. ^ Nassim Nicholas Taleb (2007) The Black Swan: The Impact of the Highly Improbable, →ISBN: “A gray swan concerns modelable extreme events, a black swan is about unknown unknowns”