Idiom: Dark Horse Posted on 1st March 201828th February 2018 by DoubleClick Dark Horse: One who was previously unknown and is now prominent. Examples: It’s difficult to predict who will win the project. There are two or three dark horses in this proposal competition. Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Posted in Idiom and tagged Idiom D.