The Interesting Story Of How “X” Came To Symbolize The Unknown

Mr. X, X-files, X-rays (remember when we talked about Why This Certain Type Of Electromagnetic Radiation Is Called “X-Rays”?), Project X, X marks the spot, “solve for x” in algebra, you name it. The letter “X” always symbolizes the unknown and is often shrouded in mystery. But where’d that come from?

Well, in his very interesting TED talk, Terry Moore, the director of the Radius Foundation in NYC, gives us the answer which he found back in 2006 when he decided to learn Arabic.

Surprisingly, the letter “X” is the unknown because the Spanish can’t say “sh”. Here’s the full story. (the article continues after the ad)

Back in the 11th century when the Arabic texts made it to Europe through Spain, the Spanish people were so fascinated with the wisdom found in the transcripts, they wanted to translate them into their own language. But there was one major problem: some sounds in Arabic are simply not represented by the European characters.

One of these characters was the Arabic letter “sheen”, this one right here: ش. You see, this letter makes the sound “SH”. It’s also the very first letter of the word “shayun”, which means “something undefined”, or “the unknown”. The problem was that the Spanish couldn’t render this into their own language as there’s no SH in Spanish. So, they used the Greek letter “κάπα” – “Κ” to borrow that CK sound from the classical Greek.

However, when this material was later on translated into Latin, the Greek letter “Κ” was simply replaced with the Latin letter “X”. When the translation occurred and essentially formed the basis for math textbooks for more than 600 years, the letter X became known as the… unknown.

And this is why, even today, the letter “X” symbolizes something we don’t know about.

Interesting indeed! Here’s the full TED Talk by Terry Moore:

If you like what you read, then you will definitely love this one: What Does The “X” in Xmas Stand For?  

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Sources: Why is ‘x’ the unknown?