dark horse

American  

noun

1. a racehorse, competitor, etc., about whom little is known or who unexpectedly wins.

2. a candidate who is unexpectedly nominated at a political convention.

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dark horse British  

noun

1. a competitor in a race or contest about whom little is known; an unknown

2. a person who reveals little about himself or his activities, esp one who has unexpected talents or abilities

3. politics a candidate who is unexpectedly nominated or elected

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dark horse Cultural  

1. An unexpected winner. In politics, a dark horse is a candidate for office considered unlikely to receive his or her party's nomination, but who might be nominated if party leaders cannot agree on a better candidate.

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dark horse Idioms  

1. A little known, unexpectedly successful entrant, as in You never can tell—some dark horse may come along and win a Senate seat. This metaphoric expression originally alluded to an unknown horse winning a race and was so used in a novel by Benjamin Disraeli (The Young Duke, 1831). It soon began to be transferred to political candidates, among the first of whom was James K. Polk. He won the 1844 Democratic Presidential nomination on the eighth ballot and went on to win the election.

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Etymology

Origin of dark horse

First recorded in 1825–35

Example Sentences

Even though the Dodgers initially had doubts about their chances of landing Edwin Díaz, circumstances changed, the reliever’s market evolved, and they went from dark horse to front-runner.

From Los Angeles Times

Xiaomi in particular was a "dark horse", she said, its debut AI glasses the third best-selling of their kind for the first half of 2025 despite only being on sale for about a week.

From Barron's

After more than a century of false starts, the dark horse of the renewable-energy industry seems finally poised to make a significant dent in America’s insatiable appetite for new sources of power.

From The Wall Street Journal

At the same time, Darnold has emerged as both a dark horse to be this season’s MVP and an incredible bargain: His $33.5 million a year contract is far cheaper than the game’s highest-paid passers.

From The Wall Street Journal

At the start of the season, we said on The Whole 10 Yards that Denver could be this season's dark horses.

From BBC

Related Words

• also-ran
• long shot
• sleeper
• underdog