未知数

(1)lacking predictability

(2)予測性を欠いていること

(3)the trait of being unpredictably irresolute; "the volatility of the market drove many investors away"

(4)予測がつかないほど優柔不断である特性

(5)a factor in a given situation whose bearing and importance is not apparent; "I don't know what the new man will do; he's still an unknown quantity"

(6)関係と重要性が明らかでない所定の状況における要因

(7)a variable whose values are solutions of an equation

(8)方程式の解答の値である変数