'bangtail' originates from American English, formed by combining 'bang' (sense 'to cut off or cut short') and 'tail' (the rear appendage of an animal).

'bangtail' appears in 19th‑century usage often hyphenated as 'bang‑tail'; over time the hyphen was dropped and the compound became the single word 'bangtail'.

Initially it referred literally to a tail that had been 'banged' (cut short); later it developed figurative senses referring to inexperience (applied to horses, jockeys, or people) and, in racing usage, to horses that have not yet won.