'archduchy' originates from the prefix 'arch-' (from Greek 'arkhi-' meaning 'chief, principal') combined with 'duchy' (from Old French 'duchee', ultimately from Latin 'ducatus' and 'dux' meaning 'leader').

'duchy' developed from Latin 'ducatus' → Old French 'duchee' → Middle English 'duchy'. The prefix 'arch-' derives from Greek via Latin and was attached in Early Modern English to form 'archduchy', notably used for the Archduchy of Austria.

Initially it referred specifically to the domain or territory of an archduke; over time it has retained that primary meaning and is used to denote such principalities or territories.