Where does “ard-duic” come from?

ard-duic (Manx) comes from Manx ard- — high; arch-, chief; excellent, noble.

ard-duic (Manx): archduke

Definitions

Step	Language	Word	Meaning
1	Manx	ard-	high; arch-, chief; excellent, noble

ard-duic — Etymology, Origin & Word History | Etymology Explorer