Why 'X' Means Kiss: A Medieval Mystery Solved

Every time you sign a text with "XOXO" or scribble X's on a Valentine's card, you're participating in a tradition that stretches back to the Middle Ages. But how did a simple letter become the universal symbol for a kiss?

When an X Was Your Signature

In medieval Europe, literacy was a luxury. Most people couldn't write their own names, let alone read a contract. So when it came time to sign important documents—land deeds, marriage contracts, business agreements—they needed an alternative.

The solution? The letter X.

But this wasn't just any random mark. The X held deep religious significance. It represented the cross of Christ and, by extension, St. Andrew's cross. Signing with an X was essentially making a sacred oath.

The Kiss That Sealed the Deal

Here's where it gets interesting. After marking their X, signers would kiss the letter—just as one might kiss a Bible when swearing an oath in court. This kiss transformed a simple mark into a binding promise, witnessed by God himself.

The act was so common that the X and the kiss became inseparable in people's minds. Over time, the letter itself absorbed the meaning of the gesture that followed it.

From Legal Documents to Love Letters

By the Victorian era, the practice had evolved. People began using X's in personal correspondence to represent the kisses they couldn't give in person. The religious connotation faded, replaced by romantic sentiment.

Some historians point to specific letters from the 1700s and 1800s where writers explicitly used X's to mean kisses. The tradition stuck, eventually pairing with O's (representing hugs, from the encircling motion of arms) to give us the "XOXO" we know today.

Not Everyone's Convinced

It's worth noting that some linguists remain skeptical of this origin story. The direct documentary evidence linking medieval X-signing to our modern kiss symbol is thin. Alternative theories suggest:

• The X resembles puckered lips seen from above
• It may derive from the Jewish practice of signing with a circle or cross
• The connection might be a Victorian-era invention with a retrofitted medieval backstory

Still, the medieval oath-and-kiss explanation remains the most widely accepted and certainly the most romantic.

A Living Tradition

What's remarkable is how this symbol has survived the death of the practice that created it. Nobody signs legal documents with an X anymore (well, almost nobody). Yet the X-for-kiss convention thrives in an age of smartphones and social media.

Every "xx" at the end of a British text message, every "XOXO" closing out an email, carries an echo of medieval peasants pressing their lips to parchment, sealing their word with a sacred gesture.

Next time you type those X's, you're not just sending digital affection—you're keeping alive a tradition nearly a thousand years old.