X factor

Wikipedia

English

Alternative forms

• x-factor
• x factor

Noun

X factor (plural X factors)

1. (idiomatic) An unknown or hard-to-define influence; a factor with unknown or unforeseeable consequences.
   • 1992, Lia Matera, Prior Convictions, page 121

     We slid into our office, past two women discussing the "X factor," an apparently undefined quality their firm felt they lacked.

   • 1999, Joel R. DeLuca, Political Savvy: Systematic Approaches to Leadership Behind the Scenes, page 75

     The map can be misleading. It can appear to contain all the relevant information, but in real life, there is always an X factor.

   • 2007, Tasmina Perry, Daddy's Girls, page 12

     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.

2. prothrombinase, also called factor X.