'monopoly-supporting' is a compound of 'monopoly' + 'supporting'. 'Monopoly' originates ultimately from Greek 'monopōlion' (from 'monos' meaning 'single' + 'polein' meaning 'to sell'), and 'supporting' is the present participle of 'support', which comes from Old French 'supporter' and Vulgar/Medieval Latin 'supportare' (from 'sub-' meaning 'under' + 'portare' meaning 'to carry').

'Monopoly' entered English via Late Latin 'monopolium' and Middle French forms, becoming Middle English/early modern English 'monopoly'. 'Support' came into English from Old French 'supporter' (and ultimately Latin roots), with the participle 'supporting' forming in English by regular verb inflection.

Initially, the elements meant 'single seller' (for 'monopoly') and 'to carry/hold up from under' (for 'support'). Over time the compound evolved to mean 'favoring or upholding single-firm market control' in modern usage.