'opisthographically' originates from Greek, specifically the word 'opisthios', where 'opisth-' meant 'behind, at the back', combined with Greek 'graphein' meaning 'to write' (via the combining form '-graphic'/'-graph').

'opisthios' combined with 'graphein' produced the combining form 'opistho-' + 'graph' in learned New Latin/Modern formation; this yielded English adjectival forms such as 'opisthographic' and later the adverb 'opisthographically'.

Initially it meant 'at the back' or 'behind'; over time the compound sense came to mean 'written on the back' or 'relating to inscriptions on the reverse side', which is the current specialized usage.