'antithetical' originates from Greek, specifically the word 'antithetikos,' where 'anti-' meant 'against' and 'tithenai' meant 'to set or place.'

'antithetikos' transformed into the Late Latin word 'antitheticus,' and eventually became the modern English word 'antithetical' through Middle English.

Initially, it meant 'set against,' but over time it evolved into its current meaning of 'directly opposed or contrasted.'