'trust-buster' originates from English, specifically the compound of 'trust' and 'buster', where 'trust' (from English 'trust') referred (in late 19th century business usage) to a business combination or monopoly and 'buster' (from 'bust', slang for 'to break') meant 'one who breaks or destroys'.

'trust-buster' developed in the late 19th and early 20th centuries in the United States to describe people and policies that broke up corporate trusts; the term was popularized in political discourse (for example referring to Theodore Roosevelt's antitrust actions) and became established as the modern compound 'trust-buster'.

Initially it specifically meant 'one who breaks up corporate trusts' in the context of Gilded Age/Progressive Era antitrust enforcement; over time it has retained that sense and broadened to mean any person, agency, or policy aimed at breaking or restraining monopolies.