shoo-in

The term 'shoo-in' originated in early 20th-century American horse racing slang. It referred to a fixed race where a jockey would deliberately hold back his horse, allowing a pre-selected competitor to win easily, as if being gently ushered ('shooed') across the finish line. From this literal scenario of a guaranteed victory through manipulation, the meaning generalized to describe any candidate or competitor whose success is considered a certainty, losing its original connotation of fraud. The logic of the word thus evolved from a specific, somewhat dishonest act of ensuring a win to a neutral term for an overwhelming favorite.

The word is a compound formed from the verb 'shoo' (an onomatopoeic interjection used to drive away animals) and the preposition 'in'. It functions as a fixed idiomatic noun.