'x-factor' originates from the use of 'x' as a symbol for an unknown quantity in mathematics, combined with 'factor,' meaning an element that contributes to a result.

'x-factor' was popularized in the 20th century as a term to describe an unknown or unpredictable element that could influence outcomes.

Initially, it referred to an unknown variable in mathematics, but over time it evolved to describe a unique or impactful quality in various contexts.