Book review Apologies to early readers of last week’s newsletter. I made two mistakes in coding the links that enable readers to buy the book from Amazon — codes should be four alphanumeric characters, but I made them five, then forgot to test them. My thanks to alert subscribers who told me about the problem. It needed 15 minutes of hurried reworking of the online translation routine, but the codes have since worked.

A black swan event is related to the butterfly effect. The latter was coined by the American mathematician and meteorologist Edward Lorenz in 1973 as a way to illustrate the chaotic nature of weather and the huge difficulties of modelling it on computers. A tiny change in the initial conditions can often lead to dramatically different outcomes. His example was of a butterfly that fluttered its wings in Brazil, setting off a tornado in Texas. (SF fans will know that Ray Bradbury anticipated the idea in his 1952 story A Sound of Thunder; a time traveller to the age of the dinosaurs accidentally kills a butterfly and learns when he returns to the present day that history has changed in a small but vital way. But Bradbury didn’t use the term.)

Black swan came into the language in 2008 because of the book The Black Swan: The Impact of the Highly Improbable by Nassim Nicholas Taleb, a former market trader. He argued that the stock market is as unpredictable as any chaotic system and that people who thought they could forecast it on the basis of past trends were fooling themselves. At the time he wrote, 2007, this was considered a contrarian view, but recent events have convinced many doubters of its truth.

For Taleb, a black swan is an unpredicted and unpredictable event, like the finding of black swans in Australia by the seventeenth-century Dutch explorer Willem de Vlamingh. It was taken for granted by Europeans at the time that all swans were white, so his finding could not have been expected and was outside previous experience.

The term has been taken up in financial circles and now appears more widely. Though it mainly refers to the recent global financial turmoil, it is also used for unexpected happenings — the closure of the London Stock Exchange for most of 10 September 2008 due to a computer failure was called a black-swan event at the time.

* Chicago Sun-Times, 10 Oct. 2008: Either the financial world as we know it is coming to an end — or it’s not! We’ll only know in hindsight. But unless this is the proverbial “black swan” — the unimaginable and unique event that annihilates capitalism — this panic will subside.

* The Press, New Zealand, 8 Oct. 2008: The credit crunch and banking crisis definitely qualifies as a black swan. No one saw it coming and no one knows how it is going to end. All we know is that it is messy.

Having a changeable, varying lustre or colour.

No two dictionaries seem to entirely agree on the current meaning of the word. Some mention only the bright lustre of a gem that’s caused by reflections from within the stone, because the word now most frequently appears in discussions by gemologists; other dictionaries include the sheen of a bird’s plumage or the changing colours and texture of a material such as silk.

All agree, however, that the source of the concept is the gleam of a cat’s eyes in the dark. The direct source is the eighteenth-century French verb chatoyer, to shine like a cat’s eyes (based on chat, French for cat). Its French connections remain so strong that it is still sometimes said as though it were a French word (/ʃætwæjɑ̃/, roughly “cha-twai-yan”).

Many examples in English literature refer to shining eyes, as in The Insidious Dr Fu-Manchu, by Sax Rohmer, of 1913: “I managed to move sufficiently to see at the top, as I fired up the stairs, the yellow face of Dr. Fu-Manchu, to see the gleaming, chatoyant eyes, greenly terrible, as they sought to pierce the gloom.”

Some of you may be jaded following recent electoral excitements in the USA, New Zealand and elsewhere. But your further and continuing help is required. Despite everyone’s endeavours, World Wide Words is dropping back in the contest for the 2008–09 Choice Awards. This is the competition organised by L-Soft, creators of the LISTSERV mailing list software on which the World Wide Words newsletter is distributed. Do please vote and keep on voting!

Ephebicide George Monbiot created this word in an article, Lest we forget, in the Guardian on 11 November: "There are plenty of words to describe the horrors of the 1939–45 war. But there were none, as far as I could discover, that captured the character of the first world war. So I constructed one from the Greek word ephebos, a young man of fighting age. Ephebicide is the wanton mass slaughter of the young by the old." The root appears in a few English words, including ephebe, the Greek word filtered through Latin, which means a young man aged between 18 and 20 who undertook military service. Ephebiatrics is a rare medical term for the branch of medicine that deals with the study of adolescence and the diseases of young adults; an ephebophile is a homosexual adult sexually attracted to adolescents. Though George Monbiot created it afresh, there is one previous example of ephebicide on record, in a work of 1979, Saul's Fall: A Critical Fiction. This purported to be a collection of critical essays about a play by a forgotten Spanish author, but the whole book, including the play, was an invention by Herbert Lindenberger, now Emeritus Professor of Humanities at Stanford University.