Serendipity means the occurrence of finding something good or valuable by accident rather than design. It sits at the intersection of luck and curiosity: the scientist who notices an unexpected reaction, the traveller who wanders into the best meal of their life, the person who picks up a stranger's dropped book and discovers their favourite author. The word captures all of it.
Core definition
Serendipity is a noun. It refers to the faculty of making fortunate and unexpected discoveries by accident, or to the fact of such a discovery itself. Merriam-Webster defines it as "the faculty or phenomenon of finding valuable or agreeable things not sought for." The key element is the combination of chance and a positive outcome. A bad surprise isn't serendipity. Finding your wallet on the kitchen counter isn't either. The discovery has to be genuinely lucky and genuinely welcome.
The adjective form is serendipitous. The adverb is serendipitously. You'll see both forms in journalism, fiction, and everyday conversation. "It was a serendipitous meeting" is perfectly natural English.
The origin story
Serendipity was coined by the English writer Horace Walpole in a letter dated 28 January 1754. Walpole drew the word from a Persian fairy tale called "The Three Princes of Serendip" (Serendip being an old Persian name for Sri Lanka). In the tale, three princes use observation and logical inference to deduce facts they couldn't have known directly, each discovery arriving through sharp attention rather than deliberate search. Walpole called this quality serendipity and declared he had made it a new English word on the spot. He was right that the word didn't exist before him. It was slow to catch on, but by the 20th century it had become one of the most recognised words in the language.
The story matters because it shapes the word's meaning. Serendipity isn't pure dumb luck. The princes in the tale weren't passive. They noticed things. They were alert. That's why serendipity implies a certain readiness of mind, not just a random collision with good fortune. Louis Pasteur's remark that "chance favours the prepared mind" captures exactly the same idea, even though he never used the word itself.
How to use serendipity in a sentence
Serendipity works best when the context makes clear that the discovery was both unplanned and meaningful. A few examples:
- "By pure serendipity, she sat next to the editor who later published her first novel."
- "The drug's most important application was a product of serendipity: researchers were studying something else entirely."
- "He didn't plan to move to that city. Serendipity brought him there, and he never left."
Don't use serendipity as a synonym for mere luck or coincidence. Winning a raffle isn't serendipity. Finding a dollar on the pavement isn't serendipity. The word carries a sense of discovery and personal significance that keeps it distinct from ordinary fortune.
Famous examples of serendipity
Some of the most useful scientific advances came about through serendipity. Alexander Fleming returned from holiday in 1928 to find mould contaminating his bacterial cultures. Another researcher might have thrown the plates away. Fleming noticed that the mould was killing the bacteria around it. That observation led directly to penicillin.
The microwave oven followed a similar path. In 1945, Percy Spencer was working with magnetrons at Raytheon when he noticed that a chocolate bar in his pocket had melted. He connected the effect to the microwave radiation from the device, and Raytheon patented the first microwave oven two years later.
Post-it Notes, Velcro, and X-rays all trace their origins partly to serendipitous observation. What unites these stories isn't passive luck. It's that the people involved were paying close enough attention to recognise what they'd stumbled across. That's the prepared-mind quality baked into the word's DNA.
Serendipity vs related words
Serendipity is sometimes confused with a few neighbouring words. Luck is broader and more neutral: it covers good and bad outcomes and doesn't imply discovery. Coincidence describes two things happening at the same time without meaning any particular outcome is good or bad. Fortuitousness and fortuity describe chance events but carry none of serendipity's sense of discovery or alertness.
The closest single word is probably windfall, but even that points more at something received than something found through active, curious attention. Serendipity really does occupy its own corner of the language. That's part of why it appears so consistently on lists of words people love and don't want to lose.
If you enjoy words that describe character and perception, you might find the definition of sagacity rewarding reading. Sagacity points at a different kind of fortunate insight: wisdom built from experience rather than chance. The two ideas complement each other neatly.
Register and tone
Serendipity is standard English, neither slang nor overly formal. It appears comfortably in literary fiction, academic writing, science journalism, and ordinary conversation. It doesn't need to be avoided in professional contexts, and it doesn't sound stiff in casual ones. That range is one of its genuine strengths as a word.
Be careful not to overuse it. Reach for serendipity when the discovery is genuinely unexpected and genuinely significant. When the moment is smaller, lucky or fortuitous will serve you better and feel less grandiose. Words like zeal and serendipity both carry real emotional weight; using them too freely bleeds that weight away.
Quick reference
- Part of speech: noun
- Adjective form: serendipitous
- Adverb form: serendipitously
- Origin: coined by Horace Walpole, 1754, from the Persian fairy tale "The Three Princes of Serendip"
- Core meaning: the fortunate discovery of something valuable by accident
Horace Walpole invented the word in a single letter. The fact that it's still here, still precise, still loved, and still doing exactly the job he invented it for is, fittingly, a kind of serendipity in itself.