biàn​shù

uncertainty

变数 (變數) biàn​shù
uncertainty noun
a variable factor or unpredictable element in a situation

The outcome of this match is still uncertain.

variable noun
a symbol or quantity that can take on different values in mathematics

The outcome of this match is still very much up in the air; anyone could win.

Frequency

Movie subtitles
1.61 per million appears in 1% of films
Written text
3.92 per million

Sources

Definitions
CC-CEDICT