X factor
noun
informal <非正式>
1
- a noteworthy special talent or quality特殊才能; 非凡品质：
there are plenty of luxury cars around, but the S-Type has that special X factor.
市面上已有大量的豪华车, 但只有这款S型车才具有非同一般的特殊性能。
2
- a variable in a given situation that could have the most significant impact on the outcome（可能影响结局的）未知因素, 可变因素。