Some Arabic words can have several meanings, depending on their context. Some are difficult to translate because they refer to something not clearly identified in other languages.
And some Arabic words are very straightforward with no hidden or multi-faceted meaning, like our Arabic word of the week, al shay'e, which means "the thing".
But what makes some words interesting isn’t their meaning but their history. In the case of al shay'e, it’s extraordinary to see how the word was used throughout history and how it has influenced the world.
Colloquially, al shay'e literally means the thing and is used to reference any topic or physical object. However, Arab mathematicians used al shay'e to mean “the thing that is unknown” in the context of mathematical formulas. Specifically, al shay'e was used to represent a number being used in an equation or defined within a formula or rule.
The Arab world's contribution to the world of mathematics is vast. This includes the concept of zero, which was originally introduced in Mesopotamia some time before 1600BC, or the work of the ninth-century mathematician and astronomer Muhammad ibn Musa al-Khwarizmi, who we have to thank for the word algorithm (which was derived from his name) and the theories within, and the word, algebra.
A lot of this knowledge and its accompanying texts, especially the one that pertains to mathematical knowledge, were brought to Spain in the 11th and 12th centuries with the intention to translate them into Spanish.
However, as many linguists will testify, language is a living thing, prone to changes, especially when translated.
The sound "sh" does not exist in Spanish and there was no character that could represent the sound or the word al shay'e. So translators and transcribers decided to use the "k" sound from classical Greek with its letter kai. As this knowledge spread through Europe and was translated into what was then the common European tongue, Latin, the Greek letter kai was replaced with the Latin X ― since the two looked fairly similar.
Given the accessibility of Latin at the time and its influence, all the mathematical material translated into Latin formed the basis of mathematical teaching and books until this day, which is why X is used to represent a value or variable that is yet unknown.
This has infiltrated the global lexicon, from phrases such as “X marks the spot” or having an “X factor” and "X-ray" or even in pop culture content such as The X Files or X-Men. And yet the reason we use X in maths to mean the unknown, is because al shay'e in Arabic means the thing or the thing that is unknown.
Scroll through the gallery below to see The National's other picks of Arabic word of the week