X factor
noun1
Idiomatic An unknown or hard-to-define influence; a factor with unknown or unforeseeable consequences.
- We slid into our office, past two women discussing the "X factor," an apparently undefined quality their firm felt they lacked.1992, Lia Matera, Prior Convictions, page 121:
- The map can be misleading. It can appear to contain all the relevant information, but in real life, there is always an X factor.1999, Joel R. DeLuca, Political Savvy: Systematic Approaches to Leadership Behind the Scenes, page 75:
2 more examples
- And put him on an LA film set and he glowed with that indefinable X-factor that agents the world over wished they could bottle.2007, Tasmina Perry, Daddy's Girls, page 12:
- Whether it's trade, global warming, Darfur or North Korea, China has become the new x factor, without which no durable solution is possible.2007 December 31, Fareed Zakaria, “The Rise of a Fierce Fragile Superpower”, in Newsweek, page 38:
2
Idiomatic A special talent, ability or quality or its indefinable cause.
3
Prothrombinase.
4
Astrophysics The proportionality constant which converts CO emission line brightness to molecular hydrogen mass.