Name: Why is 'x' the unknown?
Uploaded: 2012-06-06T15:00:59Z
Duration: 3 min 40 s
Description: Why is 'x' the symbol for an unknown? In this short and funny talk, Terry Moore gives the surprising answer.

Why is 'x' the symbol for an unknown? In this short and funny talk, Terry Moore gives the surprising answer.

Why is 'x' the unknown?

The symbol 'x' represents the unknown because medieval translators struggled to capture Arabic sounds in their own languages. When Arabic mathematical texts reached Spain, the word 'shayun'—meaning 'something' or 'unknown'—could not be directly translated, so scholars substituted Greek and Latin letters. Over centuries, this workaround turned a simple letter into a global icon of mystery, now seen everywhere from math class to pop culture.