Have you ever stopped to think why on earth do we assign the letter X to anything and everything we are not familiar with? Mutants, files, factors, numbers, rays, and many other persons, animals, objects or entities of unclear description are classified as X. Why? Well, according to Terry Moore, director of the Radius Foundation, you can blame it all on the old Spanish scholars who attempted to translate Arabic texts into the Spanish vernacular. It seems that when the texts that contained the Arabic mathematical wisdom made their way to Europe via Spain in the 11th and 12th centuries, translators found the task a lot more challenging than expected. As you would expect, some of the sounds in Arabic were not represented by the characters that were available in European languages and thus impossible to translate. The letter SHeen (below) being one of the best examples.
SHeen makes the sound we are accustomed to pronounce as SH — “sh.” It’s also the first letter of the word shalan, which means “something” , some undefined, unknown thing. In Arabic, it is possible to make this definite by adding the definite article “al”, and you’ll have al-shalan — the unknown thing.
So the mystified Medieval Spanish scholars who were tasked with translating this material found that the they could not render the letter SHeen and the word shalan into Spanish because Spanish simply did not have that SH, that “sh” sound.
So what did they do? They created a rule in which they borrowed the CK sound from classical Greek in the form of the letter Kai (below).
Imagined what happened next?
When this material was translated into other common European languages, Latin for instance, translators chose to replace the Greek Kai with the Latin X. And once that happened,once this material was in Latin, it formed the basis for mathematics textbooks for almost 600 years.
So, there you go.
Why is it that we assign letter X to everything that is unknown to us? For no other reason than the inability of some poor scholars in mediaeval times to pronounce the Arabic sound “sh” in Spanish.