archducal
/ɑːrkˈduːkəl/Definitions
1. adjective
relating to or characteristic of an archduke; of or relating to the highest rank below that of a sovereign monarch
“The archducal palace in Vienna is a stunning example of Baroque architecture.”
2. noun
a nobleman of the highest rank below that of a sovereign monarch
“The archducal family has lived in the palace for generations.”