sɛrɛnˈdɪpɪtɪ

serendipity: The faculty of making happy and unexpected discoveries by accident. Also, the fact or an instance of such a discovery

People like the word serendipity—there’s something cheerful and unexpected about that “-dipity” ending which makes them want to say it or write it, and so its original meaning has gradually eroded away. The definition above comes from the Oxford English Dictionary, but a quick search of the internet turns up a more compact version of the same thing:

Finding something good without looking for it

So merely happening on some money lying in the street nowadays counts as serendipity.

Which is a shame, because it used to mean something different, nuanced and more useful. The word was coined in 1754 by Horace Walpole, the Whig politician and author of the proto-Gothic novel The Castle of Otranto. And he wrote a famous letter to Horace Mann explaining its origin:

This discovery [a piece of useful information Walpole had chanced upon], indeed, is almost of that kind which I call Serendipity, a very expressive word, which, as I have no better to tell you, I shall endeavour to explain to you: you will understand it better by the derivation than by the definition. I once read a silly fairy tale, called the three Princes of Serendip: as their highnesses travelled, they were always making discoveries, by accident and sagacity, of things which they were not in quest of: for instance, one of them discovered that a mule blind of the right eye had travelled the same road lately, because the grass was eaten only on the left side, where it was worse than on the right—now do you understand Serendipity?

Later in the same letter, Walpole condenses his definition of serendipity down to two words: “accidental sagacity”.

Unfortunately, Walpole’s derivation didn’t really match his definition. The three princes of the story were supremely observant and sagacious—forerunners of Sherlock Holmes, in fact. From clues along the roadside they deduced that a camel they had never seen was not only blind in one eye, but also lame, missing a tooth, carrying a load of honey on one side and butter on the other, and ridden by a pregnant woman. The accidental aspect in the story is minimal.

But what Walpole seems to have had in mind, with his “accidental sagacity”, seems to be pretty much what Louis Pasteur was talking about when he said:

Dans les champs de l’observation le hasard ne favorise que les esprits préparés.
(In the realms of observation chance favours only the prepared mind.)

From a lecture at the University of Lille (1854)

So serendipity is an unlooked-for discovery, for sure, but the sort that requires a degree of observation and thought to appreciate its value. Alexander Fleming‘s discovery of penicillin is perhaps the archetype of that kind of serendipity in science—the chance observation that an unwanted fungus colony on an agar plate had killed the staphylococci growing around it. Fleming’s sagacity converted that accident into a medical revolution, with the introduction of antibiotics. The event is commemorated by the Alexander Fleming Serendipity Award, an award for a “person or organisation that built a thriving business on an idea that originated in the most unexpected or surprising way”.

Serendipity languished, rarely used, for two centuries after Walpole coined it—then it seems to have been suddenly discovered in the 1940s, and its popularity has ramped steadily ever since, as its Google Ngram shows:

Along the way, it accreted a new meaning, which has run in parallel with Walpole’s original usage, and with the increasingly common “finding something good unexpectedly” interpretation. Margot Lee Shetterly put it this way:

Serendipity happens when a well-trained mind looking for one things encounters something else: the unexpected.

Hidden Figures (2016)

The medical educator Julius Comroe, Jr. put it differently:

Serendipity is looking in a haystack for a needle and discovering a farmer’s daughter.

Quoted by Eldon Taylor, What Does That Mean? (2010)

The idea here is that it’s not merely a chance encounter, seized on sagaciously, but that serendipity happens when you’re looking for something else. Wilhelm Röntgen’s discovery of X-rays falls into this category—he was experimenting with electron beams in a partially evacuated glass tube, when he noticed that a fluorescent screen across the room lit up when he activated his apparatus. Röntgen gave up on the electron investigations he had planned, and devoted himself to studying the mysterious “X” rays that his apparatus was generating. He then experienced another moment of the same kind of serendipity. During a series of experiments in which he tried to block the penetrating X-rays from reaching his fluorescent screen, he was reaching out to place a piece of lead in the ray path, when he inadvertently got his hand in the way instead, and caught sight of the silhouette of the bones of his hand projected on to the screen.

The etymology of serendipity is pretty clear from Walpole’s letter—he took the three princes’ country of origin, Serendip, and appended the suffix -ity, which we use to generate the name of a state or condition from its adjective. So we have purity, the state of being pure; inferiority, the state of being inferior; suavity, the state of being suave, and so on. The suffix came to us from French -ité, which in turn came from Latin -itas, both of which do the same job as the English version. We have a unique case in which both the English and Latin versions are current—gravity and gravitas, performing slightly different functions.

Serendip was not a mythical place—it was the island we now call Sri Lanka. (In 1977 Arthur C. Clarke, who lived for most of his life in Sri Lanka, published a collection of essays entitled The View From Serendip, dealing with, among other things, the serendipity of his arrival on the island.) The original Persian was Sarandip, which came ultimately from Sanskrit Simhaladvipa, “island of the Sinhala people”. The Greek version was Selediba, and that seems to be the origin of the name Ceylon, by which Sri Lanka was previously known.

The Tamil people of Sri Lanka use the name Eelam, which has various competing and abstruse etymologies. Tamil Eelam is the name given to an aspirational independent Tamil state in the north and east of Sri Lanka.

A Sinhalese name for the island was Tamraparni, variously translated as a reference to copper-coloured leaves or red trees. The Greeks borrowed that one as Taprobana, which found its way into Ptolemy’s Geographia in the second century, and so enjoyed some currency in mediaeval Europe.

Arthur Clarke borrowed it (as Taprobane) for the name of a fictional equatorial island in the Indian Ocean, in his novel The Fountains Of Paradise.

And finally there was Lanka, the name of the island used in classical Indian epic poems. With the Sanskrit honorific prefix Sri, it was adopted as the name of the newly independent republic in 1972.