From Valentine’s Day cards to messages from your mom, a typical sign-off to show love and affection is XOXO. The X stands for kiss and the O stands for a hug—but why? Well, the origin of these symbols is uncertain, but we can make some educated guesses about where they come from.
Why is X the symbol for a kiss?
The use of X as a symbol is believed to date back to the Middle Ages, when most people were not literate. They would use the letter X—or a cross—to sign documents as a display of faith and indication of their sincerity. They’d also kiss the cross as another symbol of trustworthiness: a literal “seal with a kiss.” In these instances, the X represented the sign of the cross and Christ because of its connection to the Chi-Rho, a Christian symbol. The first two letters of Christ in Greek (ΧΡΙΣΤΟΣ) are chi and rho, and chi looks like X.
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It’s possible that the X also became connected with kissing because it looks like two puckered lips. No matter its history, the letter X was used in letters to symbolize a kiss back in the 1700s.
Why is O the symbol for a hug?
The origins of how O came to represent a hug are even more uncertain, though some connect its use to illiterate Jewish immigrants who came to the US who may have signed documents with an O. They did this in contrast to the Christian X. Eventually the letter came to represent a hug.
Another possibility is that the O is used to represent hugs because it simply looks like someone encircling their arms in a hugging gesture. It’s also possible that the O came to mean “hug” because of its prior association with X from the game tic-tac-toe.
The practice of pairing O with X as a sign-off in a letter as XOXO is a fairly modern one and didn’t see widespread use until the 1960s. The TV series Gossip Girl also popularized its use, as each episode ended with a signature voiceover, “XOXO, Gossip Girl.”
Despite the complicated origins of these symbols, these days it is widely accepted that XOXO means “hugs and kisses.” In the United Kingdom, use of XX (meaning “kisses”) as a sign-off is particularly popular, though the practice remains less common in North America, where XOXO is the more common formulation.
