Is Serendipity Day an official holiday?

Not in any sense that shows up in the public record: Madeleine Kay writes that she had it declared an official holiday, but names no authority and no instrument. A full-text search of the Federal Register returns nothing for Serendipity Day, while the same search returns 36 documents for Loyalty Day and 23 for National Small Business Week.

Does serendipity just mean good luck?

Not as Walpole defined it, since he required sagacity as well as accident and ruled out finding a thing you were already looking for. Merton and Barber found that some dictionaries dropped the sagacity half, which is roughly how the word came to be treated as a synonym for a happy fluke.

Is August 18 the anniversary of the word being coined?

No. Walpole coined serendipity on 28 January 1754, and no source located explains why the modern day falls on August 18 rather than on the anniversary of the letter.

Serendipity Day

Next celebratedWednesday, August 18, 2027

Serendipity was voted Britain's favourite word in 2000, ahead of Quidditch and love. Its day asks you to spend it doing one thing you would not usually do.

See how to celebrate

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Last updated September 2, 2026 · by the Holiday Calendar TeamHave an update or spot an error?

YEARLY DATEAugust 18

OBSERVED INUnited States

CATEGORYFun

SUBCATEGORYUnique

ORIGIN

Individual Initiative

FOUNDING ENTITY

Madeleine Kay

FIRST OBSERVED

~2010

“I did it! I've had Serendipity Day declared an official holiday!

HOW THE HOLIDAY CAME TO BE

The day's entire documented history is its founder's own website.

Serendipity Day is the work of Madeleine Kay, an American author and coach who calls herself the Serendipity Lady and who fixed the day on August 18. She says on her own site that the day has been made official, but names neither the authority behind that nor the year she began. The earliest documented trace of the day is 2010, when she registered its dedicated domain in June and published its first page by August.

Read her own Serendipity Day pagevia Madeleine Kay

INTRO

Britain's favourite word was printed 135 times in 204 years

Horace Walpole invented the word serendipity in a letter dated 28 January 1754, and in the same letter set a condition that most modern uses of it fail. Writing to his friend Sir Horace Mann, he described making discoveries "by accidents and sagacity, of things which they were not in quest of", then added a parenthesis: "for you must observe that no discovery of a thing you are looking for comes under this description". He called the knack accidental sagacity, which is accident plus judgement, not luck on its own.

For most of the two centuries that followed, almost nobody used it. By 1958, two hundred and four years after that letter, the word had appeared in print just 135 times. In 2000 it was voted Britain's favourite word, ahead of Quidditch, love and hope.

Serendipity Day, kept every August 18, belongs to that second life rather than the first. Its founder, though, lands on Walpole's side of the argument about what the word means.

GOOD TO KNOW

Surprising facts about Serendipity Day

Walpole turned a camel into a mule

The animal in the tale he was quoting is a camel, which three princes track down a road without ever laying eyes on it. By the time Walpole retold it to Mann it had become 'a mule blind of the right eye'. Robert Merton and Elinor Barber put it plainly: 'his memory had transformed the camel of the original story into a mule'.

The story he named it after does not show serendipity

Walpole said the princes were 'always making discoveries ... of things which they were not in quest of'. Merton and Barber checked the tale and found the opposite: the princes 'found nothing at all, but merely gave repeated evidence of their powers of observation'. They add that Walpole himself 'was looking for information about the Capello arms' and simply found it at the right moment, which is not what his own rule allows either.

Voltaire got a novel out of the same camel

The tale reached Europe in several versions, and Merton and Barber identify one of the French ones, Simon Gueulette's very free translation of 1712, as the text 'which Voltaire used for Zadig'. The same episode of tracking-by-inference fed both a philosophical novel and, in 1754, an English noun. Merton and Barber describe the princes' deductions as being of the nature of Sherlock Holmesian insights.

A Persian poem, an Armenian in Venice, and three French editions

Behind the 1722 English book Walpole read sits a long relay. Merton and Barber trace it to the Persian writer Amir Khosrau of the late thirteenth and early fourteenth century, then to Christoforo Armeno, an Armenian living in Venice, whose Peregrinaggio di tre giovani figlivoli del Re di Serendippo appeared there in 1557, then through French translations of 1610, 1712 and 1719.

The history of the word outlived both its historians

Merton and Barber finished their book about serendipity in 1958 and deliberately left it unpublished. An Italian translation appeared in 2002, after Barber had died, and the English edition only in 2004, about a year after Merton's own death. A study of accidental discovery reached its readers by an accident of publishing.

It was not his only coinage

Strawberry Hill House, the trust that runs Walpole's house at Twickenham, counts 'beefy, sombre, nuance and souvenir' among his gifts to the English language. He also coined triptology, after Dr Johnson's habit of repeating things thrice, which caught on with nobody at all.

ORIGINS

Serendipity Day history

CHAPTER 01

A discovery about a picture frame

Walpole was arranging a frame for a portrait of Bianca Capello, which Mann had bought in 1752 and sent to him in 1754. Hunting for suitable emblems, he opened a book of Venetian arms and happened on a detail tying the Capello family to the Medici.

He wrote to Mann that same day that the find was "almost of that kind which I call SERENDIPITY."

The name came from a fairy tale he had read in an English edition of 1722, The Travels and Adventures of Three Princes of Serendip. Serendip is Sri Lanka. Britannica derives that name from the Sanskrit Siṃhaladvīpa, Dwelling-Place-of-Lions Island, which Arab traders are thought to have borrowed from Indian merchants.

CHAPTER 02

Seventy-nine years in a drawer

Walpole put the word in a private letter, and private letters stay private. His correspondence with Mann was not published until 1833, so serendipity reached print seventy-nine years after he wrote it, and surfaced again only in the 1870s, in the journal Notes and Queries.

Recognition then arrived in institutional steps, well ahead of actual use. Between 1909 and 1934 it entered all the big and medium-sized English and American dictionaries, and the Concise Oxford English Dictionary took it in 1951. Robert Merton had already claimed it for research in March 1946, naming the serendipity pattern: "observing an unanticipated, anomalous, and strategic datum, which becomes the occasion for developing a new theory".

CHAPTER 03

Popular, and blurred

Fame cost it precision. Merton complained that the word had come to mean "little more than a Disneylike expression of pleasure, good feeling, joy, or happiness", and delivered the verdict that "the vogue word became a vague word". He and Barber also found dictionaries that had quietly dropped Walpole's sagacity half.

Serendipity Day arrives at the end of that story. Madeleine Kay fixed it on August 18 and still runs it from her own site, under a copyright line that reads 2010.

Two founding years circulate online, 2001 and 2003; they contradict each other and neither appears in anything she has published. Her own reading of the word, though, is closer to Walpole's than to the greeting-card version. Serendipity is often called a happy accident, she writes, and her answer to that is blunt: "It's not an accident at all!"

TIMELINE

Timeline

The book Walpole read

The Travels and Adventures of Three Princes of Serendip is printed in London. Walpole would later describe it to Mann, in the very letter that coined the word from it, as a silly fairy tale.

Walpole coins the word

On 28 January he writes to Sir Horace Mann, names serendipity, and rules out any discovery of a thing you were looking for.

The word finally sees print

Walpole's letters to Mann are published, carrying his coinage into public view seventy-nine years after he wrote it.

Merton names a pattern

In March, the sociologist Robert Merton defines the serendipity pattern in empirical research, and the word acquires a technical use alongside its literary one.

Britain's favourite word

Serendipity comes first in a nationwide favourite-word survey commissioned by The Word, London's Festival of Literature. The BBC reported the result under the headline that the country's favourite word was a surprise.

The day leaves its first trace

Madeleine Kay registers a dedicated Serendipity Day domain in June and has the holiday's first page online by August, the earliest documented sign of the observance.

BY THE NUMBERS

Serendipity Day by the Numbers

135: printed uses of 'serendipity' by 1958
15,000+: votes in the UK favourite-word poll it won
13,000: newspaper mentions of 'serendipity' in the 1990s
636,000: web documents using 'serendipity' in 2001

WHY THIS DAY MATTERS

Why We Love Serendipity Day

Sagacity

Accident supplies the moment. Sagacity is what notices it.

In the tale Walpole half-remembered, the princes decide the missing animal is blind in one eye because the roadside grass has been cropped only on the side where the grass is worse. Nothing lucky happens to them. They notice something anyone could have walked past, and the noticing is the whole trick. That is why Walpole paired accident with sagacity rather than treating them as the same thing.

Attention

A day built around changing your angle

The instruction the day comes with is unusually literal, and that is the whole of its design. You cannot schedule a discovery, but you can change where you are standing when one goes past, and a day that moves you off your usual route widens the surface something unplanned can land on. Walpole's version of the word required an observer who was paying attention, and so does this one.

Translation

Among the hardest English words to translate

A poll of 1,000 professional linguists run by the London firm Today Translations put serendipity in its top ten hardest English words to translate, behind plenipotentiary; the BBC reported the survey on 22 June 2004. The difficulty is not hard to see: the word carries accident, judgement and good fortune at once, and its inventor had to reach for a fairy tale to explain it.

GET INVOLVED

How to Celebrate Serendipity Day

Do one thing differently

The founder's own instruction for the day is to 'do something you don't usually do . . . or do something differently than you usually do it'. Take another route, another aisle, another seat. The point is not novelty for its own sake; it is ending up somewhere your usual day would never have taken you.

FACE

Face one of your fears

'Face one of your fears' sits on Madeleine Kay's own list of suggestions for August 18, alongside taking a big step toward a dream you have been harbouring. Pick the smallest version of the thing you have been avoiding and do that one today.

REACH

Reach the person you keep meaning to reach

Two more of her suggestions are to make a new friend and to contact 'that person you've been longing to'. A message to someone you last spoke to years ago costs a minute, and where it leads is genuinely not up to you.

Do something anonymously generous

Her list includes doing 'something anonymously philanthropic' and 'a random act of kindness'. Anonymity is what makes this one fit the day: you give up the return, which leaves the outcome genuinely out of your hands.

READ

Read the letter that invented the word

Walpole's coinage survives in full, and Princeton University Press hosts the chapter that quotes it in its entirety, free to read. It takes five minutes, and it is worth meeting the definition in Walpole's own words rather than in anyone's summary of it: The Origins of Serendipity.

Test your knowledge

How well do you know Serendipity Day?

1 / 6

Who coined the word serendipity?

Answer

Its founder has never published a year, and the two dates that circulate online, 2001 and 2003, contradict each other and appear in nothing Madeleine Kay has written about the day. The earliest documented trace is 2010, when she registered the day's dedicated domain in June and had its first page online by August.