'anticonventionally' originates from Modern English, specifically formed from the prefix 'anti-' (from Greek 'anti' meaning 'against') and the adjective 'conventional' (from Latin 'conventio' via Old French 'conventionel'), with the adverbial suffix '-ly'.

'conventional' entered English via Old French 'conventionel' from Latin 'conventio' ('a coming together'); in Modern English the prefix 'anti-' was combined with 'conventional' to form 'anticonventional', and the suffix '-ly' produced 'anticonventionally'.

Initially related elements ('conventio') referred to 'coming together' or 'agreement'; over time 'conventional' came to mean 'according to established practice', and 'anticonventional' developed the sense 'against established practice', with 'anticonventionally' meaning 'in a way that opposes convention'.