black swan


noun
  1. an Australian swan, Cygnus atratus, having mostly black plumage and a red bill.

  2. an occurrence or phenomenon that comes as a surprise because it was not predicted or was hard to predict (often used attributively): a disastrous black-swan event that only appeared obvious in hindsight.

Origin of black swan

1
(def. 2) from the belief that all swans were white, before the first sighting of Australian black swans

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How to use black swan in a sentence

British Dictionary definitions for black swan

black swan

noun
  1. a large Australian swan, Cygnus atratus, that has a black plumage and red bill

  2. a phenomenon that occurs even though it had been thought to be impossible

Origin of black swan

1
sense 2 from the fact all swans were thought to be white until black swans were discovered in Australia

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012