'archducal' originates from English, specifically from the noun 'archduke' plus the adjectival suffix '-al', where 'arch-' came via Greek 'arkhē' meaning 'chief' and 'duke' comes from Latin 'dux' meaning 'leader'.

'archducal' was formed from the noun 'archduke' (a title used especially for certain Habsburg rulers, itself influenced by German 'Erzherzog' meaning 'arch-duke') with the addition of '-al' to make an adjective; the noun 'archduke' entered English in the early modern period and the adjective followed by regular formation.

Initially it meant 'pertaining to an archduke' and this basic sense has largely remained unchanged in modern usage.