dark horseSEE DEFINITION OF dark horse
EXAMPLES FROM THE WEB FOR DARK HORSE
Would any dark horse, at the last moment, enter to divide the interest?
As an invalid she was taken on board The Dark Horse and confined to her cabin.
But the difficulty was that none of the crew knew the looks of The Dark Horse.
He was the first presidential "dark horse," and indeed hardly that.
Heifetz, however, may be the dark horse in the modern fiddle sweepstakes.
Oh, yes, I agreed to bring in a dark horse, and I'll bring him in all right.
But it struck me, somehow, it might be a dark horse, so I made a bid—and got it for only a sovereign!
On another occasion Malmesbury speaks of Gladstone as ‘a dark horse.’
If he's a dark horse he might rook me at billiards or bridge.
I had never heard of Jazz in those days: Jazz was decidedly a dark horse.