A mysterious or shy person who unexpectedly turns out to be the best at something.

Popularly used to describe a man who may not initially catch a lady’s attention but is then unpredictably, completely charming (and, if the lady really hits the jackpot, is fantastic in bed). Due to the element of surprise, a dark horse can often beguile even the most beautiful and intelligent ladies into bed.
‘You got Lizzie into bed? Damn, you’re a dark horse man. We’ve all been trying for months’
by MJ79 March 7, 2006
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a person or team that is no likely to win but may do so anyway
A dark horse like that could have dealt a major blow to your credibility.
by The Return of Light Joker April 18, 2010
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1. A hit song by Katy Perry
2. Someone supposed to bring about the apocalypse
3. Someone who is unnoticed but shocks everyone with a great performance.
When he won at Watkins Glen, AJ Allmendinger went from dark horse to recognized road course specialist.
by fajlkg sdfjkldfs ;jksaj djdfk; November 10, 2014
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To Dark-Horse (verb)

To act in a sly or secretive manner, rarely letting others know what you're doing, where you're going, or who you're going with.

Being a very shady character, and being quite quiet are essential to perfecting this action.

A good poker-face is obligatory, of course.
I saw Ryan buy 4 different cards for Valentines Day, he is such a Dark-Horse, i never know what he's up to.
by Herr Gilbert February 14, 2012
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One who keeps himself or his aims hidden. Keeping things secret, or concealed even seemingly pointless secrets they can be referred to as a dark horse when the interest, relationship, or action is revealed. Perhaps surprising, unexpected, even vaguely scandalous.
"Did you hear Dick won a mountain biking race?"
"Wow! What a dark horse, I thought he was a couch potato!!!"
"Trent has a new hot younger girlfriend, they were keeping it secret because he's her dad's friend"
"What a dark horse!!!"
by Ms Marple September 16, 2021
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The dark horse spent her life trying to throw everyone else off, to win at any cost to everybody else. Most of them did not know that life was thrown already.
by Solid Mantis February 5, 2021
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The dark horse was trying to throw everybody that wasn't herself off to win at any cost. None of them knew the race was already thrown.
by Solid Mantis February 5, 2021
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