A "black swan" is a scenario that wasn't covered by the training data.

Source: https://www.infoworld.com/article/3681850/12-programming-mistakes-to-avoid.html

Dr Parwinder Kaur pictured with a black swan in Matilda Bay, Perth.

Source: https://www.rawstory.com/doj-trump-documents-bigger-deal/

Majestic pictures show a rarely seen black swan feeding with a bevy of white swans on the River Severn - 9,000 miles away from the waterfowl's native Australia.

Source: https://www.dailymail.co.uk/news/article-11816247/Black-swan-feeds-bevy-white-swans-River-Severn-Worcester-rare-UK-sighting.html?ns_mchannel=rss&ns_campaign=1490&ito=1490

Nevertheless, the delta in magnitude is gargantuan, possibly indicating that traders are mitigating tail risk (i.e. black swan event).

Source: https://investorplace.com/2023/09/7-stocks-to-sell-based-on-unusual-options-activity/

Starting with interest rates, we're well off the 1.3% starting point for 5Y Treasuries and it seems unlikely we will revisit that level any time soon, barring a black swan kind of event.

Source: https://seekingalpha.com/article/4586727-cef-weekly-review-can-we-expect-cef-prices-to-fully-recover?source=feed_all_articles

The black swan events and market challenges that unfolded in the 2022 season have also led many ag retailers to change the way they do business.

Source: https://www.farmprogress.com/outlook/uncertainty-input-prices-likely-continue-2023

"The thing is they were black swan events, they came out of nowhere, were a massive surprise and we were right to do something big.

Source: https://www.bbc.co.uk/news/uk-politics-65979777?at_medium=RSS&at_campaign=KARANGA

This was the catalyst for the black swan theory, the meaning of which varies slightly between its use in economics and philosophy but is similar to “when you assume, you make an ass out of you and me”.

Source: https://www.theguardian.com/environment/2023/sep/25/bird-of-the-year-2023-forget-the-pretty-birds-and-vote-for-an-underbird

We don't see any real secular risks that hurt DDOG's prospects aside from key personnel leaving, but the chance of black swan events is always there.

Source: https://seekingalpha.com/article/4642079-datadog-stock-ultimate-garp-play-buy?source=feed_all_articles

While the 2020 recession was brought about by a black swan event in the form of a pandemic, the conditions that risk tipping Australia into a recession this year are more reminiscent of those leading into the 1990-91 recession.

Source: https://www.theage.com.au/business/the-economy/what-recession-looks-like-for-young-australians-20230612-p5dfw3.html?ref=rss&utm_medium=rss&utm_source=rss_business