‘黑马’ (hēi mǎ) literally means 'black horse' — a compound of 黑 (hēi, 'black') and 马 (mǎ, 'horse'). But in modern Chinese, it’s used almost exclusively as an idiom meaning 'dark horse': a person or team that unexpectedly succeeds, especially in competition, despite low expectations or little prior recognition. The term evokes the image of an underdog — unassuming in appearance but capable of surprising victory.

This expression is common in sports commentary, business news, politics, and academic contests. Unlike its English counterpart, 黑马 carries no negative connotation in Chinese; instead, it often implies admirable resilience, hidden talent, or strategic breakthrough. It functions grammatically as a noun and can be modified by measure words like 一匹 (yī pǐ, 'one [animal]') or adjectives like 意外的 (yìwài de, 'unexpected'), though it frequently appears bare in headlines and casual speech.