'bangtail' originates from English, specifically the compound 'bang' + 'tail', where 'bang' meant (dialectally) 'to cut short or lop off' and 'tail' meant 'rear part (of an animal)'.

'bangtail' appeared in 19th-century English (often as the hyphenated form 'bang-tail') in American and British usage referring to horses with docked tails; it later appears unhyphenated as 'bangtail' and gave rise to the adjectival form 'bangtailed'.

Initially, it meant 'a tail cut short' or 'a horse with a cut tail'; over time the sense remained but was also used adjectivally as 'bangtailed' meaning 'having a docked tail'.