'counter-hypnotically' originates from the combination of the prefix 'counter-' and the adjective 'hypnotic'. 'counter-' comes via Old French 'contre' (from Latin 'contra') meaning 'against', and 'hypnotic' comes from Greek 'hypnos' meaning 'sleep' (through Late Latin/Greek 'hypnotikos').

'counter-' entered English from Old French 'contre' (ultimately from Latin 'contra'), and 'hypnotic' comes from Greek 'hypnos' -> Ancient Greek 'hypnotikos' -> Late Latin/Greek forms; the compound 'counter-hypnotic' formed by combining the English prefix 'counter-' with 'hypnotic', and the adverbial suffix '-ally' produced 'counter-hypnotically'.

Initially the parts meant 'against' (counter-) and 'pertaining to sleep' (hypnotic); over time their combination came to mean 'acting against hypnotic effects', and the adverb now conveys doing something in that opposing manner.