black swan

• Événement imprévisible ou phénomène rare ayant un impact majeur, souvent évoqué en finance et en analyse des risques pour désigner des faits exceptionnels et inattendus qui sont rationalisés a posteriori.

An unpredictable event or occurrence that has a major impact, often used in finance and risk analysis to describe rare and unforeseen phenomena that are rationalized in hindsight.

1. Unexpected eventC1formal

   An unpredictable event that has severe consequences and is often inappropriately rationalized after the fact.

   cygne noir

   • The 2008 financial crisis was a black swan event.
   • Many experts failed to predict the black swan of the pandemic.
   • The company's collapse was a black swan that no one saw coming.

2. Rare occurrenceB2informal

   Something extremely rare or unlikely to happen.

   cygne noir

   • Finding a four-leaf clover is like a black swan.
   • A total solar eclipse is a black swan in some regions.
   • Winning the lottery twice is a true black swan.