We see it at the end of birthday cards, text messages, and late-night emails to loved ones. It’s a casual, almost automatic sign-off for affection: XOXO. These four simple letters are universally understood in the English-speaking world as “hugs and kisses.” But have you ever stopped to wonder why? Why does a letter that marks the spot on a treasure map also represent a kiss? And how did the O, a simple circle, come to mean a hug?
The answer isn’t a simple one. It’s a fascinating story that winds through centuries of religious history, medieval legal practices, and even the games of North American immigrants. So, let’s pucker up and embrace the delightful etymology of XOXO.
The ‘X’ Factor: A Kiss Sealed with Faith
The story of the ‘X’ as a kiss is the more documented and ancient of the two. Its journey from a simple letter to a symbol of affection is deeply rooted in the history of Christianity and the practicalities of a largely illiterate society.
From Christ to a Cross Mark
The tale begins with the Greek language. The Greek word for Christ is ΧΡΙΣΤΟΣ (Christos). The first letter of this word is Chi, which is written as ‘Χ’. From the earliest days of Christianity, the Chi symbol, or a version of it combined with the second letter, Rho (P), to form the Chi-Rho symbol (☧), was used as a sacred monogram representing Jesus Christ. This is why, even today, ‘Xmas’ is sometimes used as an abbreviation for Christmas—the ‘X’ stands for Christ.
This sacred association gave the ‘X’ an aura of solemnity, truth, and holy authority. In a world steeped in faith, invoking the name of Christ was the most profound way to affirm a promise. And that’s exactly what happened in the Middle Ages.
The Signature of the Sincere
During the medieval period, literacy was a privilege reserved for the clergy, nobility, and a small merchant class. The vast majority of the population could not read or write. So, how did an ordinary person sign a legally binding document, like a contract, a deed, or a sworn oath?
They would make their mark. The most common and legally recognized mark was a simple ‘X’. By drawing this symbol, the signatory was not just making a random cross; they were invoking the name of Christ as their witness and swearing upon their faith to uphold the agreement. The ‘X’ was their bond, a sacred promise made before God.
But there was one more crucial step. To demonstrate their sincerity and to physically seal the oath, the person would then kiss the ‘X’ they had just drawn on the document. This act of kissing the mark was a physical manifestation of their sworn oath, much like kissing a Bible in a modern courtroom. Historical letters and documents from the era often end with a description of this practice, with the writer noting that the signature was “sealed with a kiss.”
Over time, this powerful association stuck. The physical act of kissing the ‘X’ became so intertwined with the symbol itself that the ‘X’ evolved to mean “kiss.” When people began writing personal letters, especially in the 18th and 19th centuries, closing with an ‘X’ was a shorthand way of sending a kiss and sealing their affectionate words with sincerity.
Cracking the Code of ‘O’: A Hug’s Humble Origins
If the history of the ‘X’ is a well-trodden path, the origin of ‘O’ as a hug is more of a winding, overgrown trail. There isn’t a single, definitive “aha!” moment like the medieval signature kiss. Instead, we have a few compelling theories that likely all contributed to the ‘O’ becoming the embrace we know today.
Theory 1: The Visual Resemblance
The simplest explanation is often the most appealing. Look at the letter ‘O’. It’s a circle. What does a hug look like from above? Two arms encircling another person, forming a circle. This symbolic, visual representation is easy to grasp and may have been a natural evolution. As ‘X’ settled into its role as a kiss, people may have sought a similarly simple symbol for its companion gesture, the hug, and the ‘O’ was the perfect visual fit.
Theory 2: The Game of Noughts and Crosses
Another popular theory points to the game known as Noughts and Crosses in Britain and Tic-Tac-Toe in North America. The game uses ‘X’ and ‘O’ as the two opposing marks. Since ‘X’ already had an established meaning as a kiss, some speculate that its game-board partner, ‘O’, was simply adopted as the symbol for a hug. While this theory is widespread, it lacks strong historical evidence and feels more like a convenient folk etymology than a definitive origin.
Theory 3: The Mark of the Other
Perhaps the most convincing historical theory comes from the wave of immigration to North America in the 19th and early 20th centuries. Many Jewish immigrants arriving at ports like Ellis Island were literate in Yiddish and Hebrew but not in English or the Latin alphabet.
When asked to sign immigration documents, they were often instructed to make their mark with an ‘X’. However, for many, making a cross—the foremost symbol of Christianity, a faith from which they had often fled persecution—was unacceptable. Instead of the ‘X’, many chose to sign with a circle, or ‘O’.
As a result, on official forms and in everyday interactions, the ‘O’ became the mark used by those who would not, or could not, use the ‘X’. It functioned as the ‘X’s’ alphabetical and cultural opposite. As ‘X’ was being solidified in popular culture as a “kiss”, it’s plausible that its contrasting symbol, the ‘O’, was adopted as the “hug” to form a complete, affectionate pair.
Putting It All Together: The Rise of ‘XOXO’
The pairing of ‘X’ and ‘O’ into the familiar “XOXO” likely began in the late 19th or early 20th century in personal correspondence. The first documented use is hard to pin down, but by the mid-20th century, it was a common, informal sign-off. The letters offered a quick, charming, and symmetrical way to convey both kisses and hugs.
The digital age has only amplified its use. From early emails to modern-day text messages and social media captions, XOXO remains a powerful piece of communication shorthand. It’s a cultural touchstone, famously used as the signature sign-off in the popular TV series Gossip Girl, embedding it further into the 21st-century lexicon.
So, the next time you dash off an “XOXO” at the end of a message, take a moment to appreciate the journey those letters have taken. You’re not just typing symbols; you’re participating in a rich history that spans religion, law, immigration, and the simple, enduring human desire to connect. Each ‘X’ carries the echo of a solemn, medieval promise, and each ‘O’ represents the simple, powerful comfort of an embrace.