dark horse

What it means

A dark horse is a person, team, or contestant who isn't well known or widely expected to succeed but who surprises everyone by performing very well. It's used in elections, sports tournaments, music competitions, and business — anywhere a surprise contender outshines the favorites.

Examples

• She was the dark horse of the election and won by a landslide.
• Watch out for that startup — it could be the dark horse of the industry.
• The dark horse of the tournament beat the defending champion.
• He's always been a bit of a dark horse; nobody knew he could sing.

Where it comes from

From 19th-century English horse racing slang, describing an unknown horse whose form had been kept 'dark' — secret — by trainers, often to gain better betting odds. Benjamin Disraeli used it in his 1831 novel 'The Young Duke'.

Related idioms