'antagonistically' originates from Greek, specifically the word 'antagōnistikos,' where 'anti-' meant 'against' and 'agōn' meant 'contest.'

'antagōnistikos' transformed into the Latin word 'antagonisticus,' and eventually became the modern English word 'antagonistic' through Middle English.

Initially, it meant 'opposing in a contest,' but over time it evolved into its current meaning of 'showing opposition or hostility.'