'establishment-supporting' originates from Modern English, specifically formed by combining 'establishment' and the present participle 'supporting'. 'Establishment' comes from Old French 'establissement' (from verb 'establir') ultimately related to Latin roots meaning 'stable/stand', while 'supporting' derives from 'support' (Old French 'soutenir', from Latin 'supportare') where the elements 'sub-' meant 'under' and 'portare' meant 'to carry'.

'establishment' passed into Middle English from Old French 'establissement' (and earlier from Latin-derived roots) and came to mean an established institution or ruling order; 'support' developed from Old French 'soutenir' and Latin 'supportare' meaning 'to carry from below' and later 'to back or defend'. The compound 'establishment-supporting' is a modern English formation combining those elements with the participial '-ing' to make an adjective.

Initially, elements meant 'to make stable' (for 'establish') and 'to carry from below' (for 'support'); over time these developed into the senses 'institution/established order' and 'to back or endorse', and the compound now means 'backing the existing authority or institutions'.