'anti-monopoly' originates from the prefix 'anti-' (from Greek 'anti', meaning 'against') combined with the noun 'monopoly', which itself derives from Greek 'monopōlion' where 'monos' meant 'single' and 'polein' meant 'to sell'.

'monopoly' entered English via Late Latin 'monopolium' (and Medieval/Modern Latin) from Greek 'monopōlion'. The compound 'anti-monopoly' was formed in modern English by attaching the prefix 'anti-' to 'monopoly' (appearing in hyphenated form in 19th-century political/economic writing) and later also seen as the closed form 'antimonopoly' and related derivatives.

Initially it simply signified being 'against monopoly' as a stance; over time it also came to denote specific laws, regulations, and institutions (e.g., antitrust/competition laws) designed to prevent or control monopolies.