'anti-Orthodoxly' originates from a combination of the prefix 'anti-' (from Greek 'anti-' meaning 'against'), the adjective 'Orthodox' (from Greek 'orthodoxos'), and the adverbial suffix '-ly' (from Old English '-lic'/'-lice' forming adverbs).

'Orthodox' comes from Greek 'orthodoxos' ('ortho-' meaning 'correct, straight' + 'doxa' meaning 'opinion, belief'), passed into Late Latin as 'orthodoxus' and into Middle English as 'orthodox'. The prefix 'anti-' is inherited from Greek 'anti-' and has been used in English since Classical/early Medieval periods. The adverbial '-ly' developed from Old English '-lic'/'-lice'. The compound 'anti-Orthodox' and its adverbial form are productively formed in Modern English.

Initially, 'orthodox' meant 'having correct or straight belief' (from Greek), and over time it came to mean 'conforming to established or traditional doctrines'; 'anti-Orthodoxly' therefore developed to express opposition to those established doctrines.