someone with a secret, especially a secret ability, skill or achievement that surprises you when you discover it;
someone or something whose abilities, plans, or feelings are little known to others
Related words and phrases:
Two friends are talking ...
Friend 1: I always thought Laurence was rather shallow and superficial.
Friend 2: I saw him reading a book of Renaissance poetry yesterday.
Friend 1: He's a bit of a dark horse, isn't he?
Two colleagues are talking ...
Colleague 1: So, who's going to get the promotion?
Colleague 2: It seems like either Vanessa or Stan. They seem like the obvious candidates.
Colleague 1: There could be a dark horse in the competition.
Colleague 2: What do you mean?
Colleague 1: Maybe there is someone who has been keeping a low profile. Someone who is more than qualified and has been working toward the position that we don't know about.
Colleague 2: I suppose that is a possibility.
There is no gerund form for dark horse.
1) Iowa State is also 3-0 and could also be positioning itself as a dark horse of sorts if it wins its third straight versus Tuberville.
2) The film seems like a sneaky Oscar dark horse -- especially if the complete feature packs as much of an emotional wallop as its ...
3) It's not like they're beating a dead dark horse. They're just throwing it out there and taking a look.
4) ... and it's conceivable that he has a dark horse chance of going ahead and upsetting Djokovic to reach the final.
5) Carter became the governor of Georgia. In 1976, he was the dark horse candidate for president.
6) The stampede toward Willkie, the quintessential dark horse candidate, puzzled informed contemporaries.
7) Mariners' team which was supposed to shock the world -- they were the dark horse to win the whole thing.
8) He was called a "dark horse" candidate because he was not expected to beat his opponent.
9) ... hoping he can become a dark horse contender in the coming weeks who draws social conservative voters unhappy with the front-runners.
10) Holly Horton - TSN I still consider Holly as the dark horse in my list. When she had just started, she very raw and her ...
11) His name was even being tossed around to make a potential dark horse presidential bid to challenge Obama in 2012.
12) I'm pulling for dark horse in this.
13) Apple's the dark horse in this race, and probably the biggest single threat to Amazon's dominance.
14) As for Bonifacio, he could be the dark horse in the deal if indeed he is to be included by the Marlins.
15) The once dubbed dark horse of the Country music industry in Canada went through some of his darkest days yet ...
16) ... or one of those dark horse candidates that never seemed to materialize.
17) I was the President Polk of the pageant, a dark horse, or maybe just a bad joke.
18) Then a certain new up and coming billionaire of industry or a new political dark horse appears and captures the ideals of millions of people.
19) Enter the new millennium and the dark horse that was collaborative law began sneaking up.
20) Any possible dark horse would, he said, remain silent until the summer.