a dark horse
idiomPart ofdark
a dark horse — idiom
1. a person who keeps their abilities, interests, or plans hidden from others, ofte
1.idiom
Definition
a person who keeps their abilities, interests, or plans hidden from others, often surprising people by winning or doing well
Example
No one expected the new chef to win — she was a dark horse in the competition.
Hugo turned out to be a dark horse who could speak five languages fluently.